Could I be pregnant!? Plz help am very scared

So I got my mirena IUD in July of this year and have been able to feel my strings and everything since my implant but my period is so irregular still I don't know if my period is late I've only been using mirena as a contraceptive and no condoms or anything with my boyfriend I've suddenly got sore Nipples sometimes I'm nauseous and light headed or dizzy and on top of that I am getting a lot of pure white discharge as well as going to the bathroom more I can't tell if I'm being paranoid or these are actual pregnancy symptoms since I've never been pregnant before I'm only 18 and I can't afford to have a baby I'm pro choice so I know that I'm ok with that option but I never want to have to go through something like that plz help I'm really freaking out about this *side note I did take two pregnancy test that both came out negative