No period since Nov 2014 and before that it was 2.5 YEARS!

Please help. I'm 33 years old and have always had irregular periods. I go for a year or more at a time. I've seen different doctors and none of them give me any answers. The last dr refused to do an ultrasound! I want kids and am afraid I will never be able to have them. My last period was in November of 2014 and the one before that was in May of 2012. Any insight? I'm so distressed and depressed over this. What should I do? I'm aware I may have PCOS but have never been diagnosed.