It doesn't really sound like your GP knows very much if their single go-to solution when 100mg of utrogestan wasn't working, was to tell you to stop HRT. For that reason alone, I'd be looking for another GP or seeing a private menopause clinic going forwards. You are just going to hit roadblock after roadblock trying to make a GP work beyond their level of knowledge and competence.
If you were bleeding on 100mg utrogestan, the first thing to try would be to increase that to 200mg and even 300mg (which is what I take). If none of that worked, then you could have tried any number of progestins including the combination patch if you were just on 50mcg estrogen (as that's the dose in the combo patch), norethisterone, cerazette, and more. If none of THOSE worked, then there is also the Mirena coil which almost always stops all bleeding no matter how much E you need to use.
Seeing your GP failed at the first hurdle here and appeared not to know anything about all these options, I'd be looking for another GP...
