Pregnancy symptoms on depo provera

Hi everyone! I am on my 3rd shot of depo (getting 4th in 2 weeks) and have recently been feeling pregnancy symptoms. Is it just in my head? I need help! :(

The first thing is that some smells have been making my gag/want to vomit.

For the last week or two my boobs have been sensitive and sore and my lower back has really been hurting.

This morning I threw up twice. I have nauseous for 3 days but didn't think anything of it until I threw up today. I don't know what morning sickness feels like though..

Also about 5 days ago I got some spotting for about 3 hours and it was darker than my periods (which I don't have regularly because of my depo so I don't know if I missed it or not)

I don't know if I should buy a test because if it's negative I will probably just end up buying more to be 100% sure. Thanks for reading and let me know what you think so I don't freak myself out!