Getting so many mixed signals!

Okay so on paper if I wrote all my symptoms down I'm basically pregant. Obviously in real life (test done 2 weeks ago) I'm not. It's confusing the hell out of me and I swear my body is just acting like this to annoy me. I have heartburn every morning, boobs are sore, can't touch my nipples, cramping, bad back, headache, no period, bit of a funky smell and brown discharge like black basically. So all theses things would make anyone say 'are you pregnant' but no, I'm on the depo and I'm pretty sure it's just that. I'm not spending another £12.99 on a clear blue test to get a negative. Urrrggghhhhh this is so frustrating. Does anyone have any tips for heartburn/acid reflux that I can do without buying medication (money is tight)? Thank you ladies and sorry I just had to let this out! Xox