Feeling nauseous & tired a lot lately

I need someone opinion so I have irregular periods and I just past my estimated ovulation last week sexual intercourse happened. I don't know how to figure out what's accurate and what's not. Lately I've been tired alot and yesterday there has been several occasions where I felt dizzy. I had to sit down one happened while I was in the shower while the other one while i was cooking. My fiance and I have been trying for a year and it's been a lot of negatives so far and with my periods being irregular I don't know what is real and what's not to be honest it could all just be stress so I don't know what to do it would be my fiance's and mine first child so I'm kinda freaking out a little bit.