if your periods are that far in between, i'd defintely get it checked out... when they said your ovary was enlarged did they mention anything about pcos?? like tarobinic said though, your hormones should have been abnormal if it was pcos, which can be a factor in long cycles.. the good news is your young, so it really does take people almost a year to get preg many times.. so hopefully nothing is wrong.. however, i know i'm not a patient person.. so finding a reason as to why your cycles are longer is a good idea, and sounds like your doing all the right things! :) i'd make sure they tested your LH, testosterone, estrogen, progesterone when they did the blood work! i have a friend who had very long cycles and they got preg after 8 months and was your age! : ) she is about to deliver! GOOD LUCK to you! keep us updated!
If your ovaries looked good, then I would take that as a good sign. Most couples can take up to a year to concieve, Ive read.
You could get an HSG to see if you have any blockage in your tubes and also have your partner get a sperm quality test to make sure all of the swimmers are good to go!
Did your OB mention if your lining was also the right thickness? That was one of my problems, my lining was too thick b/c I barely had a period and I wasn't ov. But I had PCOS, which it seems unlikely that you do b/c your OB, I would think, would have seen signs of that on your ovaries.
A word of advice, there are many many things women are told that can help them concieve, some reasonable and some just way out there. I work in a hospital and day after day I see women that are not very healthy (drug users, no prenatal care, etc) that deliver babies, some healthy and some not but the point is they were able to get pg. Yes, there are things like having a good diet, exercising and taking care of yourself that are good to do in general. I hope you see my point here. Im trying to save you the frustration I had when i was ttc. I drove myself and DH nuts with trying to be the "perfect specimen" to become pregnant.
Good luck!