Hopefully a few systemic users with expertise will be along soon. I've no expertise, but started HRT just under a year ago, aged 68. In that time, I've been put on patches, gel and now spray. Bloods were taken eventually and my levels were through the floor. This is all through an NHS specialist clinic. They tend to start you off very gently at this stage of life and absorption can be an issue as they seem to think is the case with me. (I'm only on oestrogen as hysterectomy). So, it's kind of early days for you and a very knowledgeable member explained to me that it takes all the cells three months to respond to the changes HRT creates and adapt (or not) accordingly. Hope this helps at least a little. Have you confidence in your gp? If not, it could be worth asking if there is a menopause-trained gp at the practice and if not, ask for a referral to a specialist clinic. I think it's wise to have careful monitoring by someone with enthusiastic, supportive knowledge! Good luck.