If it makes you feel better you aren't alone! I was tight before I had my first child, but afterwards it was even worse. We made the lame joke that I must have been stitched up too tight, but it took literally over a year for me to loosen up and not have painful sex. Even now there are times where my husband isn't able to finish, I'm so tight that its clenching too much for him
I find as well if I am able to orgasm at least once before penetration I relax more and can be more receptive.