Well, I was in a pretty similar situation to you. I had dyspraxia, and was incredibly socially inept, and clumsy too boot, at least for the first couple of year or two secondary school. My social skills improved dramatically during that time, but of course the first two years had pretty much set my social status, and there was nowt I could do about it. Then I changed school for sixth form, and everything got better almost immediately. Firstly, people were more mature, so if I did make a social impasse, they were more likely to overlook it. Secondly I was much better socially, and I didn't have a history dragging me down.
Of course, because I was no longer being bullied, my happiness and self esteem levels increased dramatically, so I ended up losing quite a bit of weight.
I now find i'm quite popular with the girls, and although my past social ineptitude occasionally rears its ugly head, things are going well for me.
Incidentally, i also took a gap year, and having to cook for yourself, and moving around all the time help alot with weight loss.
So to sum up: Change school, as soon as you can. You're unlikely to make progress where you are. Take a gap year, you can use that to make up for lost time in acquisition of social skills.
As with regards to money... That is of no relevance. While i don't come from a poor background, my parents fell pretty heavily into debt, so they don't have any money to give me. This may be a guy thing, but as long as you don't have a problem wearing the same clothes week after week, and searching the bargain bins, you can actually dress rather snazzily. I've been accused of being "rich" and "posh" on multiple occasions, despite living entirely off of my student loan.