Vagina not as tight as it used to be

My husband and I have been in a loving relationship for over eight years now. We have two children the youngest is 4 years old. After giving birth 4 years ago things have just not been the same for me during sex. It's just not as tight as it used to be. I understand that is to be expected after giving birth, but it is a real concern. I have always been very tight and even sore after having intercourse. I can barely tell that we've had sex aferwards now.

We keep things fun and exciting and it's always pleasurable. I do orgasm with oral stimulation and touching. I have done everything from kegels to most recently (at the advice and prescription of my DR.) been using a vaginal stimulation therapy machine to help improve vaginal muscle tone. This has not helped either. I do have some urinary incontinence and slight problems retaining a tampon. (How embarrasing)!

My husband says he does notice a difference in the tightness, but it's not a big bother to him. I can't see how it wouldn't be. He has a large penis. It used to not be a problem. I can't feel anything on the inside while he's in there.

My Dr. says I have a small opening. I agree. I do feel the initial penetration. I spoke to him about having surgery to tighten things up on the inside. I did research that shows it's entirely possible. He examined me and says I'm not as loose as I feel like I am....he thinks surgery will make it too tight.

I'm lost. I'm only 27 years. old and don't want to have this on my mind all my life. I want the maximum experience out of sex that I used to have....I just need advice and if all you guys don't mind sharing some of your experiences with me...what do you think...same with the ladies....??? Need the advice please....