I love the lucky stories!
We were the same as you TTC for 4 years. But ours was endo and and couple of other little things - not unexplained.
I bf Ds1 and didn't get cycles back until I weaned him. We didn't use protection, but I really didn't feel I could cope with the disappointment and waiting and ups and downs. Then we decided to do a frostie trf as they weren't as expensive back then. DS 2 was conceived first time. Which amazed us all.