I would like to ask for advice regarding the search for postdoc.
First a bit of background. I got my 3-years PhD in February in mathematics (applied math + numerical analysis). I am disappointed because I did not do anything important: I studied a specific numerical method with a code that was already developed (a very complex fluid code) before and then I used the method to study a physical problem (actually running a lot of simulations and analyzing the results). For that last part, I also used some ideas from dynamical systems but again nothing new. The approach however was new but it was not even mine. It was my supervisors. In the end, my thesis was in computational fluid dynamics. I got 2 publications plus 1 procceeding from this thesis, but they were all in engineering-like journals.
Back to the present. After the above experience I had a change of heart. I want to find a postdoc in applied math where I can study a problem more rigorously, but I love working in interdisciplinary subjects like biology, neuroscience, physics, fluid dynamics. The problem is I am too much of an engineer for the mathematicians. I applied to three postdoc positions and was rejected at all three.
My actual fear here is that I cannot undo the mistake I did during my PhD. How can I persuade someone to take me as a postdoc in another area/field without strong publication record? Even if I have failed I really want to continue working in research. I love science and the learning process.