I have my period every month, but is usually a week late. I had sex with my then boyfriend in August right before my period, but still had a normal period in August and had a heavy one in September(3rd-5th). I am now 3 weeks late, close to being 4 weeks late soon(and FYI I haven't had sexual intercourse since August). I took a pregnancy test a week ago and it was negative so I marked pregnancy out. I do have PMS symptoms that are a lot like pregnancy symptoms too, such as off an on headaches, abdominal cramps, back cramps(sometimes it is lower back and sometimes it is my whole back)I am tired more easily, and have mood swings for no reason. I just have never had period symptoms but no period. I looked up reasons why my period could be late such as stress(which my stress level is a 3 out of 10 so I marked that out), extreme weight loss or gain, and exercise which I also haven't been doing/experiencing. I just wanna know if I could be pregnant or if the problem is more serious.
Thanks in advance!