I am glad you have found the site and I hope that we can offer you helpful support and information!
Generally, one ovary can produce enough hormones for a woman. When a woman has two ovaries, they both do not produce ovaries each month. Instead, only one ovary functions each month. When one ovary is removed and a woman is left with one ovary, that ovary simply does the job every month.
With your hysterectomy being 12 years ago, it makes since that your remaining ovary may not be producing enough hormones for you. With time, our ovaries start to decrease hormonal production as we start to go into menopause. Peri-menopause can begin around the 40's.
Also, because you have an endometriosis diagnosis and have had prior surgeries, it is very possible that your remaining ovary was not as healthy as it should have been and thus has not been functioning properly.
Additionally, because the blood supply to the ovaries is interrupted during a hysterectomy, if a new, good blood supply is not established the remaining ovary can cease to function well.
It is good that you have found a specialist. One thing you do need to keep in mind is that with an endometriosis diagnosis, any estrogen replacement you use has potential to cause any remaining endometriosis to grow. One way to try to prevent this would be to also use progesterone.
Be prepared to need several weeks before you see any change in how you feel. It can take patients and trial and error to find the right hormonal balance. Keep a journal of all of your symptoms and plan to be in it for the long haul. Hopefully you will start to notice some immediate differences, but it could take awhile before you notice a complete difference.
Know that you are not alone and that there are many ladies here going through hormonal issues who can support you along the way!
Oh, there is no spell check as part of HysterSisters. I have spell check because I use FireFox as my browser so you could consider that as an option. Or, type your posts in a word processing program and then copy/paste them to the site.