Trying to conceive?

I've been married for four years now. During my first year marriage, I got pregnant. But then I had to abort the pregnancy due to some abnormalities. Then I took a course for 2 years whereby I could'nt get pregnant so I'm on planning. After I graduate, I'm not planning anymore. So I've been trying to conceive but failed each time my periods come. I feel so dissappointed. what should I do? My in laws always hope for a baby from me. I'm so stress. I tried not to think so much. But it didn't work. Help me!