Morning Mrs. C - I had a large fibroid 12 years ago along with endometriosis but had a hysterectomy, best thing I ever did.
Have you had an ultra scan to determine if they are definately fibroids ? Not sure how long they would take to shrink after the menopause. If you are on HRT I would think this would aggreviate the situation, pumping hormones into you etc etc. I think there are alternatives available to shrink the fibroids, I would get a second opinion Mrs. C, it sounds like they might be pressing on something to cause you so much pain.
My diagnosis - get back to the Docs and ask for a second opinion.