I'm no doctor, so I need to say up front that what I say is in no way 'professional advice'.
There are waaaayyyy too many factors in fertility for someone to be able to give you accurate advice here. Pregnancy is very chancey, miscarriages are unfortunate but they are not uncommon and as you said, it could easily be bad luck. My advice would be to make sure you don't dig yourself into negativity, and don't fixate on self-diagnosis until you know for certain there is a problem. Research and self-education is good, but I've seen too many people get depressed because of their inaccurate self-diagnosis.
As far as getting back on the PB wagon, I started by cutting out food groups one at a time. Breads and pastas at first, which was the hardest part for me, then the rest soon followed easily enough. I made a few easy steps along the way, like simply switching my potatoes for sweet potatoes, and then reducing my intake of them over time (I was eating a LOT of sweet potatoes at first).