a question for women on HRT

I had bloodwork done outside of my regular clinic and I am trying to make sense of it. I will see the gynecologist at my clinic on video in November and would like to prepare questions for her.

I am on Mirena and the lowest dose of Estradiol (I use Vivelle-Dot patches). I have been on Mirena since 2004. Not the same IUD, obviously, but the same type. I have been on Vivelle-Dot for one year. I am 52, soon to be 53. I do not have any overt symptoms of menopause or perimenopause. I had a very late menarche in case this is relevant (I was just 2 weeks shy of 16).

Mirena initially erased my periods (back many years ago), but now I spot on it more and more regularly. Last time it was even enough to wear a thin pad for one day. Usually the spotting is so light that I do not need pads.

Here is my bloodwork:

Estradiol (pg/mL) reference range 19 - 144, my level 20
Progesterone (ng/mL) reference range, 0 - 21.5, my level 0.5

These are reference ranges for ovulating women, I would think.

Still, considering that I am on HRT, aren't my levels a tad low? I wonder if I should be taking a higher dose.

I have never had this type of blood test done before and I do not know what my levels were in the past; nothing to compare to.

I have a very heavy skeleton so osteoporosis is not a concern now, but down the line, wouldn't it be better to have a little more estradiol in the system to protect my bones??

If you are on HRT, what is the target range for estradiol and progesterone for you? How often do you get tested?