Legally, it's rape.
However, rape from a moral/ethical/personal perspective is about more than just the law.
I'm rather of the opinion that if you must ask if you have been raped, that you haven't been raped. There would be ways of describing the incident more accurately.
It seems that it made you feel badly about yourself, and I would encourage you to understand your feelings on the matter, and then sit him down and talk the matter through with your boyfriend. Have you told him how it made you feel?
In everything, you need to make sure that you respect your yourself and your feelings - express them respectfully but firmly, listen respectfully , maintain respecting your feelings (which may or may not involve disagreeing with him), and if necessary, never stay in a relationship where you will not be respected...doing so says that you deserve disrespect, and repeatedly putting yourself in such a position will mean that you will eventually come to believe that you are worth the lower level of respect you settled for.