RE "unexplained fertility" - exact same thing happened to us.
We waited until we were "ready" (are we ever "ready"? certainly didn't feel like it when the baby arrived!) but it took about 4 years to actually have the baby. Miscarriages, then just nothing apart from endless mechanical & unromantic sex day after day after day for years, with deeply upsetting emotional consequences when nothing happened.
Everything checks out medically and the doctors cheerily just say "keep trying!" but then write "unexplained infertility" on your report as you plod back home for more fruitless intercourse. No one can explain why it is not working as the usual battery of tests they do come back fine ... you begin to envy and resent people you see who are pregnant, you cant look at a cute puppy/kitten because you feel like you'll never have a baby, you simmer with inner rage when someone at work brings in their baby to show around the office, or someone mentions their kids etc ..."HoW cAn thEYy bE sO INSENSITIVE?!?!?!?!" you fume to yourself as you die a little inside. It is quite the existential torture.
To HNers reading this: If this sounds like you, please do yourself a favor and find a clinic that deals with immune-related infertility. During consultations for starting IVF, one clinic casually noted that my wife had "natural killer" CD16+ and CD56+ cells that might be causing the miscarriage and no natural pregnancies. We immediately found a clinic that specialised in treating that condition and 2 months later we had a natural pregnancy that went full term - our baby boy was born 1 year ago and he is thriving. After 4 hard years of sorrow and misery, it just took some basic immune-modulating drugs and we got pregnant naturally after just two months, and a totally textbook baby (straight down the middle on weight & size etc) was born naturally with no complications. It can happen - good luck.