How do i know if im truly in love?

How do i know if i am truly in love with him? It is only high school, but its been 7 months and we tell each other "i love you". We do physical things, but not sex. And I'm just not sure that i know what "love" truly is. He asked me if i still love hm and i didnt know what to say. I feel like he loves me but im scared to say i do or something. What is love? Im not sure i guess.