It took me over two years to conceive my DD. It was awful. The few months before I finally got pregnant with her were the lowest of the low.
We're on month 6 of TTC #2. I didn't wait very long (started trying in June, she turned 1 in July). I seem to have a new problem this time, I've gotten pregnant twice and lost both. I'm glad we started a bit sooner than we felt ready since clearly this will take time.
I think it's better to think long range. You are only what 33 or 34? You have time. You want one more child and you have many years to do that. It will most likely happen, just maybe not on your exact time schedule. I give myself this pep talk all the time. I want at least one more kid, it will happen, it just might take time. I try to enjoy the sweet child I DO have and relish every day of her being my only.
Hang in there, have sex, and hopefully it happens soon for you!