Why am I not as fertile as others?

I got pregnant by surprise at 22 and it ended in an early miscarriage at 6 weeks. Then I got pregnant again at 25 from trying after 8 months. Now I'm 27 and my son is 20 months and don't understand how I'm not pregnant yet. Everyone around me gets pregnant within a year or 2 after having a baby. Not sure what do I need to do or take? It's depressing that I'm not as fertile as my friends. I also work full time and get no government benefits at all. It makes me sad that most women can stay home and get help from their partner and the government.