I've been ttc for 2nd time for the last 9months with no success, the 1st time i conceive at three month after, is there something wrong now?

Likely not: About 85% of normal couples may take up to a year to conceive, so you are well within normal at 7 months. For women over age 36 we now suggest fertility evaluation after 6 unsuccesful months, but at 24 Y.O. That is more aggressive than you need be. Most doctors, particularly fertility specialists, are glad to help you at any point though.