So depressed!

Why am I not getting pregnant?!  There's nothing wrong with me or my husband.  I have a 2 1/2 year old son and got pregnant in September on our 2nd month trying that ended in mc 2 weeks later.  Since then every freaking month is a disappointment!  I'm 7dpo this month and besides one really sore boob and my chest being insanely broken out I have no symptoms.