So do you think that taking the utrogestan on its own won't cause any problems like bleeding or anything?
It shouldn't do, because the endometrium is not being stimulated, and it is perfectly safe to take as monotherapy.
In fact there are a number of clinicians who really advocate for progesterone alone - this practice became quite common in the wake of the WHI when estrogen was maligned and everyone was afraid to prescribe or take it but women were still desperate for relief from miserable symptoms. There is some evidence that hot flushes are also reduced at higher doses of progesterone.
Whilst I don't believe this is the best option for the majority as most of the gains in quality of life and long term health come from estrogen, it is a valid option for those who either don't want or perhaps haven't tolerated estrogen.
However as there is currently no evidence to support any long term health benefits with progesterone alone, I personally believe it should only be used if it is providing symptomatic benefit in some way, such as improved sleep, and not taken primarily in the hope of improving future outcomes e.g. osteoporosis prevention or cardiometabolic health. This is not to say it definitely doesn't help in these areas, but as we just don't know this is not a current indication.