How do I know if I'm pregnant when on depo?

I've been on depo for 3 years, I've been having sex at least once a week with my boyfriend for almost a year. I have to urinate often, sometimes it's almost impossible to pee, even if I have to go really badly, my boobs are still growing for some reason, my bras don't fit anymore, my stomach is sensitive, other people seem to think I've been more "dramatic" lately. My boobs are slightly sore every once in a while. I feel like I've been gaining wait but I'm too scared to weigh myself for some reason (I'm a very small person). My stomach is sensitive lately. I haven't gone to a real doctor in a few months. The last time I took a pregnancy test was at the end of April, just for a check up. And I don't have periods.