Thanks for your query.
If you had unprotected sex and you bled on penetration, chances of pregnancy
However, please remember that you have had continuously negative pregnancy tests
Also, an ultrasound
- if pregnancy had been there, the radiologist
would have informed you, irrespective of whether you asked him or not.
Also, you are having regular periods as per the dates you mentioned.
i think you are stressing out for no reason.
The only way to confirm your doubt and to reassure yourself is to visit a gynecologist, and get an examination and a confirmed opinion.
Also, please have protected sex in the future, and take care.