Heartburn

Before I had Seth I had heartburn maybe 5 times in my life. I seriously wish I could go back to basically never having heartburn. 

During my pregnancy I started getting heartburn and had it throughout most of the pregnancy. That was not fun! 

It's now been almost 7 months since I've been pregnant and I still get heartburn. It's not as bad as it was during pregnancy, but it is still way to often. I'm tired of feeling sick, I want to feel normal!

Sooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo.....

Can anyone tell me what it is about pregnancy and after having a child that causes heartburn to go out of control? 

Ok I know that weight can be a factor and that tight clothing can also have a role in it. But I weigh less than I did before I was pregnant and I'm wearing clothes from before the pregnancy so I just don't get it. Anybody want to help me out?