Is It All In My Head???

I get my period between 28-31 days normally, but ocasionally get it late. Last month I got it on June 26th, this month it was 4 days late (started on july 29th) but came on just like a normal period for me (bad night sweats the 2 nights before, moody, sweet tooth, oily skin, then the day before I get it I always know because I am freezing all day, then horrible cramps). I had cramps all night and the next day and lots of clots and tissue for the first 2 days, with medium flow. Then the next couple of days it was lighter, turned brownish like it usually does, then stopped. What is weird is that right before I got it and currently I have hard nipples. My boobs are not sore and are not any bigger, just my nipples are more erect. I was pretty stressed out before I got my period, I know that stress can cause menstruation delay and I do have diagnosed panic disorder and general health anxiety. I am also wondering if stress could be causing this weird thing with my nipples?? Or could it be a hormonal imbalance?? I tend to interpret every little detail of my body, hence the health anxiety, and I have been known to give myself symptoms after reading things. I have a bunch of friends who are pregnant right now and that is the LAST thing I want. When my period was late, the first thing I thought about was oh sh** what if I'm PG?? I kept dwelling on it and started looking up stuff on the internet about PG symptoms. Then I finally got my period and I felt relieved, but why the weird nipples still? I swear I have read to many posts on these forums and scared myself. Anyone else have similar experience???? Phantom preg maybe????