Tired of trying.

I'm 21 years old, was diagnosed with an auto immune disease called Autonomic Dysfunction plus an hormonal imbalance issue called insulin resistance. I was on this birth control rod called Nexplanon since I was 16. From 2010 to 2014. Got it taken out July 2014 been having unprotected intercourse with my fiancé since then, didn't start my period back till November 2014. I would skip a month then it would start again, so it has been extremely confusing. It was either skip a month or have two in a month or a super long period for like 9 days. It's been killing me, my fiancé and I are at the point of giving up. Is there anyone struggling with these issues and at my age even? I know being in my early 20s that should be the most fertile point of my life and apparently it's not. My fiancé is 25 so he's not at the age where men need to worry. Is there any advice or should we start considering IVF or something of that source?

Thanks!