I was going to suggest physio but it sounds lioke you have we;; and truly done that. Do you see a specialist pelvic floor physio? Have you had a second opinion from another physio or urologist?

After having DD1 I had some prolapse issues although no incontinence. After seeing a physio for approx 6 months I had no symptoms except the first 1-2 days of AF. Her reccommendations were pelvic ffloor exercises, not lifting heavy loads,weight loss, avoiding constipation and she said once I stopped breastfeeding things would also improve (she didn't say to stop, just told me that when I chose to stop the change in hormones would improve my pelvic floor. For me this all helped and I while Ihad an uncomfertable prolapse after dd3's birth with excerises it was aback to normal (for me) within a month. She said things that you can't change were family history/genetics (Im in a similar boat to you) and that statitically the first and fourth child do most damage, and that a significant amount of perlvic floor damage is attributed to pregnancy not birth, so a c/section birth can still leave the mother with significant pelvic floor damage. She also said instrumental deleviries have a slightly higher risk of pelvic floor damage too.

Do you have any prolapse? Surgical repair is not advised until you have finished having children as subsequent birhs can undo the surgicla repair, but seeing a specialist can help as in some cases topical application of estrogen or a pessary can improve symptoms. Unfortunately being overweight can also worsen pelvic floor issues so weight loss helps

Good luck, its hard when people don't talk about these things. Oh and I can't do star jumps or skipping anyomre as it seems to worsen things but thats about all I can't do now (well things I cant do because of my pelvic floor, my lack of co-ordination on the other hand.......)