Why doesn't he want to be alone with me? Did he stop liking me or is he nervous?

I've had a crush on him since i met him in the beginning of summer...Everyone could tell he was attracted to me..He's tried to kiss me like 3 times but I always got shy and pushed him away. On one of those nights, i told him i had a crush on him and then I let him kiss me after a while.after that, i went on a trip and he asked my sister about me and she said i didn't mean anything i said or did that night.but he still came to my house when i got back to say happy birthday to me.i hadnt seen him for about a month since then bc after that, he got a dui after a frat hazing.he's also really dorky and probably thought i wasnt interested so i made the first move by inviting him over to watch a movie at my house and he said yes.i asked him for friday but he was busy so he asked me out to the movies monday night (he's friends with my brother and asked him if it was ok to take me to the movies) but on the "date" he brought his brother and his gf..which i thought was weird. It didnt seem like a date and he didnt try to make a move but we had a great time tho and talked a lot and by the end of the night he said we should hang out again soon (he seemed kinda nervous, during the movie his leg kept bouncing and when he spoke to me he got really close to my face). The other night he asked my brother if he could come over our house to hang out but my brother didnt want to pick him up. so i texted him a week ago about hanging out one friday and he seemed excited about it..so i texted him again yesterday to see if he was busy tomorrow night and he said he couldnt come cuz he had work..but said we should do it another day of the week for sure...the weird thing is...he told me to invite 2 other friends too...why? I wanted to be alone with him. (I'm 18, he's 20 by the way and im leaving for NYU aug 24) I'm just really confused lol what should i do? i dont want to seem desperate but he's obviously not getting the idea (i just want to make out with him..thats it..nothing serious since im leaving anyway)