Fee - I had the same problem , we tried once after birth and it was so painful we didnt try again until about a week or so ago. There was about 3 months inbetween DTD.. and it actually didnt hurt at all the 2nd time.
Maybe you just need some more time to heal ??
Then again , the 2nd time i was much more relaxed about it - my state of mind might have helped too - the more you stress about it , the more tense your muscles are.
I understand you though , Im scared to try the 3rd time incase the 2nd time was a fluke.

These are the things no one tells you will happen when you get pregnant !
Good luck with everything !!