So, this is kind of a different situation. As the title says, my partner's had a vasectomy five years ago and he's 45 years old. 

I've taken an at home pregnancy test and it came back negative. I was at rest for awhile but now my boobs are sore, I have cramps, but still no show of period. I read up on it and found out that pregnancy symptoms and PMS-ing are similar...HOW CONVINIENT. 

I'm aware that vasectomies can fail but over the past five years he's never gotten anyone pregnant, either.

Could it be that since a sterile guy is finishing inside you, your body has a way of thinking it's pregnant so it's messing up your cycle? 

By the way I'm 19 years old so it definitely can't be menopause or anywhere close to that.