Vaginal itching and burning, also spotting. Is it a UTI, my birth control, or having intercourse?

I'm 16 and I have been sexually active for the past 6 months, with the same person. I'm also on birth control, depo provera. And I'm planning on getting off of it this coming up month, my next appointment for my next shot is for the 7th of February, and for the past week or so I've been spotting sometimes light and sometimes fairly heavy, and it smells awful, not your typical period smell it's like 10 times worse and I've been having vaginal itching and burning, but it only burns when I pee and after but only for a few seconds. I have no idea if this is a UTI or just my depo causing all of this or an affect of having sex. But I would really like to have some advice before I go to the doctor because I hate doctors. So please any advice you could give me would be awesome.