Is it obligatory to repeat prayers, fasting, and Umrah, given that I was unaware of the proper method of ghusl after menstruation for a long time, and performed ghusl incorrectly?

There are two ways to perform ghusl (ritual bath) after major ritual impurity (janabah): a complete method and a sufficient method. If water is made to cover the entire body with the intention (of ghusl), then the ghusl is sufficient. If the ghusl was incomplete due to a lack of intention or because water did not cover the entire body, then the missed prayers must be made up, and the umrah must be made up if it was performed during menstruation, while your fast is valid in all circumstances.