First time that I'm 4 days late

I just went to the bathroom and saw on the toilet paper a tiny glob of darkish goop and realized I wasn't on top of my period this month. I recently just got my first full-time job this month after finishing school so I've been preoccupied.

This is the first time I've been 4 days late and I'm extremely scared. So far I'm hoping the darkish goop I saw is a good sign and I've been extremely constipated these last couple of days. I've also become very bloated and I've been eating like I've been a bottomless pit.

I may be overreacting, but I'm really scared. My boyfriend and I don't use condoms and we only have sex on the weekends because we still live at home with our parents. I'm 21 and I've switched to the Mona Lisa 5 copper IUD in February.

I'm hoping someone can reassure me that this is normal and has maybe had a similar experience. I'm stressing out right now.