My boyfriend wants to makeout while having me sit on his lap. helppp?

i dont know if i want to makeout while sitting on his lap because i dont want to seem like a sl**. we just started dating and stuff and i personally think we are too young to be making out (we are both 13). I mean i dont have and issue with kissing or anything because i mean that is so bad. But making out WHILE sitting on his lap (in the movies) i dont know about that. :( i already told him i dont want to makeout because i think we should take it slow and all but then somehow he convinced me into doing this. Now, i seriously dont know how to tell him NO again without seeming mean or making him upset. Yes i do know what you are going to say, "if he really was the right guy for you, he wouldnt rush you into making out." but i really like this guy and he already told me he loved me? i dont know!! i dont want to seem like a sl** if it gets out we were making out. I mean lots of other kids makeout but i dont know.. help what should i tell him!? thanks and please no mean comments! thank you (: