Feeling depressed

My partner and I have been trying to conceive for 6 months now. I'm only 20 and he's 24 so yes I know, not a big deal. We're young it'll happen everyone says. I just know in my heart somethings wrong. Everyone we know is getting pregnant. His ex, my cousin, people at work, my sister and now his sister. None of these people were even trying!! I feel extremely hurt and jealous of them and it's hard to be happy. We thought we'd get pregnant straight away and have the first grandchild and everything would be OK. Now thats not happening. Is there something wrong with me? It's my antidepressant meds making me infertile??  I cry at the longing for a baby that I have so much love to give. I want to give up :'(