Hello dear,
I understand your concern.
It's good to know that you have all the reports normal.
In my opinion there are various causes for
bleeding during pregnancy like :-
1)Thyroid abnormalities .
2)
Progesterone insufficiency.
3)Abnormal pregnancy like
miscarriage or ectopic pregnancy.
4)Bleeding from cervix.
etc.
So as per your information all the above causes might have been ruled out by physical examination and necessary investigations.
Ultrasound helps to know the well being of fetus as it is normal you need not worry.
Don't worry in some cases even though with the presence of bleeding everything will be normal and pregnancy continues till term and have good outcome.
May be the bleeding might be from cervix.
Anyways relax.Avoid physical stress and intercourse.
Take prenatals and progesterone supplements.
It might subside spontaneously.
Take iron rich diet and
iron supplements to combat anaemia caused due to bleeding.
Hope this helps .
Best regards...Dr.Srilatha