Aarrgghhhh!!! Frustrated

Just found out that a good friend of mine is pregnant (whoopsy) im happy for her but i feel sad/frustrated at the same time coz ive been trying for 8 months now. When i found out all i wanted to do was to cry so i did when i left her house and still am very upset. Im so frustrated at my self for not being pregnant yet and i now NEED it to happen this month. Im just so aarrghhh !!!!! As im writing this im balling my eyes out. I just dont understand how its so easy for some to get pregnant while others struggle. In the 8 months we have been trying three of our freinds have fallen pregnant by mistake and yet we are struggling to the point where my hubby is rethinking if he wants to have another baby.