There are things called Keigal exercises that you may want to look into. They will help strengthen those muscles.
Hi, ther are times when things will feel differant, but then thats life, our bodys change every day weather we are men or women, but thats just the nature of the human body.
And we cant change that, just enjoy what you have, and as you b/f should know by now there are times when you will feel differant, just as he may feel differant.
Good Luck
Your vagina does get more wet pre mentraul so if you have sex by it being so wet it does'nt feel the same I go thru that that my signal to let me know it's that tme of the month. Also take a couple of days off from sex give your vagina a chance to tighten back up