Ahhh I’m scared

So ladies I’ve been on mirena for 6 months and at first when my period came it was excruciating and then the next couple months after that my flow was so light (I’m usually extremely heavy flow) and I had no period symptoms as to where I usually have cramps, tender breasts, and bloating like crazy! Then the last 3 or so months my period has lasted around 10 days and now I’m 4 days late had some cramping and some spotting and that was it 😰😰😰 should I wait a few more days or take a pregnancy test! Im 20 y/o now and I’ve had my menstrual cycle since I was 12! And it’s ALWAYS been irregular until I stopped messing around with birth control! At 12/13 y/o I was put on the pill because my cycle was so heavy and the pmsing was insane I was missing a few days of school every month! Constantly having to bring extra clothes with me to school Incase I bled through! And I was on the pill on and off for around 3-4 years! And I say on and off because when I was like 13-14 y/o I had had my period for almost 2 months straight! It stoped for like 4 days max and then it came again so my doctor was playing around with different pills and all that stuff! I stopped the pill and went to the nexplanon at around 15-16 because I had became sexually actively and I was trying to be safe! Well that did the same thing! It was making my cycle very irregular I’d bleed for a couple days then have a little spotting through out the rest of the month the. The next month I’d have my period for a couple weeks and it was just really messed up! And after I got that out when I was 16-17 I went all the way till 19 without any birth control and my cycle was heavy still but it regulated its self my period was about 4-6 days each month and the. I just got put on mirena back in October and And I can’t say it’s irregular but it lasts longer than it should and now I’m 4 days late!! HELP!! What should I do??