It' so hard when you want to get pregnant and can't. Have you tried acupuncture? Lyn Swirda in Brookline has a great success rate, maybe you just need some energy balanced and stress relieved. If you successfully got pregnant 2 times then your chances are good it will happen again, uness age is a factor (like 45).
Relax, rest and eat well and try not to worry. You never know what might happen. Maybe give yourself a cut-off time to stop trying. Like an age, pick 38 or whatever you're comfortable with and then back off with the urgency and take a break. Then if that age or cut-off is reached then you can grieve, or you might not feel as much grief as you thought you would.
Good luck, enjoy what you have!