What is going on with my body?!?

Let me start put saying that we have 2 beautiful daughters! Me and my husband had difficulty conceiving our first daughter. We tried for about 2 years before we conceived. When we decided to try for a second one, it was a much easier time. We were pregnant again in a few months! Now we decided we want a third baby and we have been trying for over a year again and nothing. And I believe that I'mthe problem. Ever since having our second daughter, after my period finally came back, i have been extremely irregular! One month yes, 2 to 3 months, nothing. 2 months regular, then 2 months nothing again. I am currently on day 64 of my cycle when i was always 30 days before and even in between my kids. I kept hoping that i was pregnant this time but all the test i took have been negative. Is there something wrong with me? Im 33 years old. Could i be entering premenopause? Am i not too young? I changed insurances this year and honestly haven't been to see my doctor this year yet. Any insight/advice would be appreciated.