I think if your having gas issues it might be a build up of pressure during sex depending on the position you're in.
It happens to me when I'm in the doggy position & lower my torso. It creates a build up of air pressure & sometimes pain. So I need to adjust the position. Is that what you mean by gas??

Most women don't have orgasms during penetration....from what I've read. It's definitely possible, but not ideal.
And having children does not always equal losing the ability to be tight.