Think I might have endometriosis :/

This ia very much a TMI post, I apologize in advance. I am 28 years old. We have been trying to get pregnant for over a year now. 4 months ago I noticed I was spotting about a week before my period. I was so excited, I really thought it was the tell tale signs of pregnancy I was waiting for. But the day before my period was due I had started and it was really heavy (sorry, TMI).

Since then, I have been having issues about a week before my period with spotting after a BM. At first it was only when I strained but lately it's been after any BM within the week window. I am not sure but the first instance I mentioned I may have had a BM when that happened too. My periods are also different, some regular but more brown and skirting off early. I've taken pregnancy test that have all came back negative. I Googled my symptoms (worse idea ever) which said it could be 3 things: endometriosis, cancer, or pregnancy. I just don't know what to think. My mom had a tilted uterus and didn't get a positive on my brother till she was 6 months. I've experienced a lot if weight gain this year, it seems like more in the past couple months. I just don't want to be one of those "I had no idea I was pregnant" women.

Any thoughts on this or is anyone going through this? I just feel so alone, I am a week before my af is due to arrive and I am spotting again :(