All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
It is clear that you are affected with Waswasah (obsessive whispers); so we warn you against it, and we advise you to get rid of it and not get carried away with it, as getting carried away with Waswasah leads to a great evil.
If a person has doubts about an act of worship after having finished it, then he should not take this doubt into consideration. If he doubts having washed a part of his body that must be washed in Ghusl, then his Ghusl is valid and he should not pay any attention to this doubt.
However, if he is certain that he did not wash this body part, then successive washing is not a condition in Ghusl according to the view of the majority of the scholars. Therefore, he is not obliged to wash it immediately, but whenever he washes it, it is sufficient and his Ghusl is valid.
In the light of the above, you should know that the Ghusl in the cases you asked about is valid.
Allah knows best.