I've been trying to get pregnant for four months with no luck. what is wrong?

Probably nothing!: While one might conceive anytime you have intercourse in mid-cycle, it doesn't happen as easily as many suppose. It takes couples an average of 6 months to get pregnant and generally is not considered of concern unless you try for a year without success. Relax. Take a good prenatal vitamin, eat a healthy diet and time intercourse to the 3 days before ovulation. See http://tinyurl.com/hb4uce5