I started my PhD about a year and a half ago in an area that I will call A, which is quite applied. I've been doing a lot of programming and coding, and although I've learnt a lot and we've been doing some progress recently, I strongly feel that I haven't got any important result worth of appearing in a doctoral thesis. Even when we complete our current project (something that, I hope, is going to happen already in the near future), I won't feel like I've done any truly significant/original work. It is a nice work, but we've spent way too much time in a problem and we just don't have many results or important conclusions. I've been working on developing methodologies and improving little things, but I haven't got any concrete scientific result yet.
However, in the last 4/5 months we started thinking about a different problem (in collaboration with another professor) in a different area, B. B is a more theoretical area, and although A and B are loosely related (and ideally our work in B would be at some point applied to our work in A), they are very different topics. The thing is that I'm very happy with our progress with B, where recently I finally managed to do some hard computations and reach some interesting results with which I'm quite satisfied. Now, I feel that continuing our work in B could be really fruitful and -since we already have several ideas and plans- could soon yield some very interesting stuff. In combination with what I have already achieved, I definitely deem this work worthy of a doctoral thesis.
The problem is that B was, at least initially, a side topic, and my grant and my initial doctoral project was clearly associated to A, but not B. Working in A I feel like I'm stuck: yes, I write code and I do stuff which is sort of important, but I am spending a lot of time in something that it is not yielding very relevant results and that I don't think is going to give enough material for a thesis. However, A is like my main topic and I can only spend bits of time working on B once in a while.
That's why I've been thinking about the idea of discussing with my thesis advisor the possibility of changing my main research topic and start focusing on B, while keeping A as a side topic. He is a very nice person and has always been helpful and supporting, but I fear he is not going to take it well, since he clearly has more interest in A and has always thought of B as something nice but that "shouldn't distract me too much".
Maybe I should just accept things they way they are, or does it make sense for you to talk freely about my concerns? I don't intend to fight or anything, but having at least a conversation about the whole thing would be nice.
Any similar experiences to be shared? Ideas?