Hi - I am similar age to you and on Femoston

I used to be on the combined pill and, especially in latter years, got a headache in the week off that was like my brain shrinking and rattling round my head every time I moved. At first I thought it was migraine without an aura, and then I found out that there was such a thing as an oestrogen withdrawal headache. This was probably it.
What I found was that it was triggered by getting thirsty. So around the time it was due to happen, I would make sure I did not get thirsty - so good glass of water on waking, and carry a bottle around to drink if I felt the slightest bit thirsty, with plenty tea breaks. Beware on warm days and travelling when you can easily find yourself thirsty. The other thing was to take the painkiller of choice (mine was nurofen plus which is ibuprofen and codeine - paracetamol did not actually work at all) at the first hint.
Yours might not be this, because you are taking oestrogen all the time - do you get any other symptoms around this time? It is worth keeping a diary of symptoms sometimes. I do wonder if the addition of progestogen takes away some of the effects of the oestrogen at times.