After my graduation, I planned to have some months off to work on hobby stuff, and build a small portfolio with programming projects. Unfortunately, I wasn't able to finish my thesis in time (which is my own fault, but at my university it was also business as usual to take more time than planned for your master thesis). I already had a job and didn't have any time off between my thesis and working (in fact, I started working before I even graduated).

I should have spent some more time on job hunting, in retrospect. At my current job as a consultant I am back-end code-monkeying in a large team where most developers don't have a technical background - it's not very challenging from a technical perspective (even though I like the working environment in other aspects). My current employer pushes me to get certified for some front-end technologies, which I don't find interesting (and have no value for the gig I'm currently assigned to).

My true interest are OSes, drivers, optimization, FPGA's, electronics, compilers, assembly, microcontrollers, graphics... But I can't seem to find a job in that field, mostly because I don't have work experience in those fields. I also have a tendency to be very humble about my experience, which I think is a good thing in general, but I think sometimes people wrongly classify me as 'very junior'. On top of that, everybody seems to be looking for C# programmers, but the pay seems to be a bit lower in more technical fields. I don't care that much about my salary, but right now I am the one with literally the best background (4 academic studies), and the lowest income (basically every time I talk about it with someone, he/she goes "hm, that's pretty low"). I have had some good offers (about 15% more than I currently earn), but they came with a traineeship which seemed not very challenging and would force me to stay with that company for 2 years.

A very common scenario I end up in is that I'm talking to a very enthousiastic HR person ("I think you're a very good fit for our company!"), but the offer ends up very low ("Well, you're a junior after all.").

I am thinking about quitting my current job to brush up some skills (mainly Python, Vulkan, OpenGL, and some OS API stuff) and build a portfolio, but I'm too afraid to be unproductive and end up in a worse situation than before (about 1 year of working experience and a giant gap in my CV after that). Has anyone been in a similar situation? Any advice?