@ElizaBennett - My doctor had told me about the lower estrogen during breastfeeding. He said that's why breastfeeding seems to help protect against breast cancer; basically anything that lowers your lifetime exposure to estrogen (like if you happened to be a late bloomer) will help with that.
I have one of those aunts who's a bit too forthcoming (single lady, active social life) who was telling me all about the estrogen options post-menopause. Apparently, you can use an estrogen cream or something like that inside your vagina instead of having to take pills or shots. That way, it doesn't enter your system as much and you don't have as much risk of serious side effects, but you can still treat dryness.