Feeling useless!! 😢

Hi ladies, 
So we've been TTC since I came off cerelle in August 2015, since then my periods have slightly returned but still very irregular, I've been to the doctors, my blood tests came back normal for hormone levels and other tests, so apprently no reason why I shouldn't be having periods or getting pregnant.
I'm at a loss and feeling useless especially as everywhere I turn friends are getting pregnant 😢 I'm happy for them but can't help but feeling angry too.Â