when I was pregnant with my son I thought the same thing. I asked my ex to fist me to make it less painful. its amazing how much it can stretch. but as long as you continue to do your kegals it should go back to just as tight as before. I've had many guys say i was just as tight as a virgin, and I've had a child. its all in the muscles. try progressivly widing dildos til you can take a 4in with ease. just keep doing your kegals. they will always help tighten things back up. another thing with tightening up would be yoga exercises.