!!! So I really, really need to know !!!

So I sometimes miss my period and I lost my virginity last month on the third three days after I lost my virginity I went and got depo I've been having unsafe sex with my boyfriend since then since we're both clean. I didn't get my period at all last month which didn't surprise me since it's a side effect of depo but I suddenly started bleeding during sex a day ago. After sex I realised that it was spotting and not the normal period blood that I'm use to. I've also been getting really dizzy and I have started getting really bad back pain. I have honestly never had spotting before in my entire life and I'm nervous that I could be pregnant since every one in my family is really fertile and have gotten pregnant while on contraception. My sense of smell is also really strong so strong that smells are giving me a headache which confuses me since I have a blocked nose.