Pregnant?

Okay so I have sex quite often with my boyfriend and I’m on the depo and because I’m on it I don’t ever get my period.. me and my boyfriend also use unprotected sex and lately my stomach has been making weird noises it looks like I’ve gained weight but I’m not sure I’ve been getting cramps, headaches etc. But I took a pregnancy test a couple weeks ago and it was negative but because I don’t get my period I can’t tell. And idk what to do. pregnancy test are expensive as well