You yourself answered your own question.
But remember that the hormonal background just doesn't change by itself.
First sex is quite a stressful situation.
Physical and psychological health - one medal.
An integrated approach always works. If a person wants to do something, of course.
Most likely you have an individual hormonal reaction. You need to pass general blood tests and consult an endocrinologist.
Such situations occur in the female body when the "body expectations" do not meet - either you started sex too early, or too late. But this is not global. That is, exceptions are possible.
Also. It is worth paying attention to whether your menstrual cycle is out of order. If yes, then you are undergoing restructuring of the body from a girl to a woman, and in places adipose "savings" tissue may begin to be deposited in order to prepare the body for possible childbirth.
Try an intense workout in the fitness room, get hormone tests, eat more vegetables and drink more water. In any case, you really need an endocrinologist's consultation.