To start off, I'm a 17 year old boy and a junior in high school

I have always felt confident in my looks, and my self esteem has been rather high up until literally two days ago. Two days ago, while sitting in German class, this jerk just started calling me a gay prick. For whatever reason, he targeted me. I am secure in my sexuality (as a heterosexual) but his comments seemed to have triggered this feeling of inadequacy in regards to my physical appearance. I have a girlfriend of 4 1/2 months and she has said many times that I am very handsome and what not. Despite her saying this, I have a hard time trusting that she
actually is attracted to me. I tell others of my concerns and they think I'm being ridiculous, like, "Of course she is attracted to you. If she wasn't, she wouldn't be dating you". Again, I have never felt unattractive in my life up until this point (excluding the worst year of everyone's life, 8th grade), but suddenly I don't feel attractive. Is my girlfriend being truthful? Do I have a basis for these worries? Thanks