but the thing is i loved the stuff that was covered in school, and I want to apply it
I'm going to give you an outside-the-box suggestion that may or may not intrigue you: consider going into a different field where you can apply the topics that interest you. A lot of mathematics historically was developed in conjunction with other sciences to help describe the natural world. Look at Karl Pearson and Ronald Fisher and their contributions to the life sciences.
Here's how this might look for you:
- Find a field that interests you and has a need for mathematicians. Extremely math heavy fields like physics might be harder to get into because they'll have higher base standards of math, but other "softer" sciences like sociology, economics, psychology, biology, ecology, etc, do not have that same expectation. Research in these fields ranges from very applied to very theoretical. The problem is, most people that go into these fields are not very advanced in math, so the theoretical end of the spectrum tends to be lacking. This could be your niche.
- Go into a master's research program in said field. A master's won't necessarily give you the flexibility to do exactly what you want, but it will give you necessary background in the field and help you decide if you want to continue this route. Master's research programs are generally paid; you won't necessarily make a lot of money doing it, but unless you're waiting tables at fancy restaurants, it's probably not going to be much worse. You shouldn't have to take out loans for a MS degree doing research.
- Then go onto a PhD program where you have the flexibility to do what you want with math. This could be applying advanced mathematical concepts in a novel way to the field you are now in, or maybe even finding a way to use your new field to drive discovery of new mathematical concepts. The pay situation is similar to a MS. Meanwhile, depending on the field, your course requirements are probably going to be flexible enough that you can probably take graduate math courses as part of your PhD program.
- Postdocs are an optional step that may appeal to you. They give you more flexibility in defining your own research.
- Going into an academic research position may be your end point. Here, you have the flexibility to define exactly what you want to research, how theoretical/applied it will be, and develop a lab of graduate students with similar interests to help support you while you simultaneously support and train them.
Now, I'm going to give you some perspectives/examples about this from my view as a wildlife ecologist/geneticist/programmer:
First: ecology, in particular, is interesting because it is a nexus science that incorporates virtually every other field you can imagine, including physics, chemistry, law, economics, geology, biology, psychology, etc. This means there is a lot of flexibility in how people curate their interests and careers.
Second, going into grad school, I had a strong background in computer science and well above strength in math (I've always enjoyed math and almost switched to mathematics in my undergrad). Programming and math are both very valuable in ecology, and especially rare for incoming students to have any level of proficiency (most students only have a rudimentary calculus background, if that, and no programming experience). My background has given me a huge advantage in conducting advanced and interesting research. I'm actually planning on taking some of the graduate-level math courses in things like modern analysis, linear algebra, etc, and my advisor, who is not a math person but recognizes its importance in theoretical ecology and genetics, is very supportive of this.
Third, ecology, and probably other "soft" sciences as well, tend to be flexible about the backgrounds of incoming graduate students. I did have a background in biological sciences from my undergrad, but I know people that have come from completely different backgrounds. In one case, a friend did her undergrad and masters in some form of engineering (mechanical?) and worked for NASA. She then completely shifted gears and started a PhD in quantitative ecology and had a successful degree doing black bear research. Being able to pitch a strong math/engineering background is what got her in, despite no background in ecology that I'm aware of.
Fourth, related to the previous point, it's common in my field for people to start grad school late. I started my MS 5 years after my undergrad. I know people that started their PhD's in their mid- to late-thirties. Age isn't so much a factor for developing a career in some fields like mine.
Fifth, ecology, and other sciences as well, develop many theories based on mathematical concepts. It's really common for these theories to be developed based on mathematical concepts that are decades old (or older); often they just weren't applied earlier because people with the necessary background and expertise to do so are rare. So there's plenty of opportunity to do this type of thing. Network/graph theory is one relatively recent example in ecology, and the application is still relatively rudimentary.
Fifth, related to the previous, I recently was involved with applying absorbing Markov chains to predicting the dispersal and mortality of wildlife populations across landscapes. This process involved interdepartmental collaboration with mathematicians/engineers to develop the relevant theory.
If I've piqued your interest, just start looking into different fields, the theories they operate under, and the math underpinning those theories. I can't speak for other fields, but in ecology I can point you to quantitative ecology and theoretical ecology. That's just a starting point, because math is ultimately relevant to all aspects of ecology. In my case, I'm interested in theoretical population genetics in ecology, which is also very math heavy.
If you find something that interests you, then consider finding university researchers that do related work and try digging into what they do specifically. Contact them to discuss their work and how someone with your type of background could potentially become involved in their field. Some might not respond, but others will be very supportive. Ultimately, your success down this path will depend less on your formal education and more on how you pitch the skill and background you have, as well as your ability to show initiative.