I need serious help...

I've been dating my boyfriend for almost 3 years. I have given him literally everything. I am the one that waits for him to say when we do something and I jump to do it. I will ask him and he will say i dont know yet, idk what my parents have planned. keep in mind he is almost 21 YEARS OLD. I have been a good sport about this for a long time. And anything he ever said he wanted I bought for him. Or even things I saw I'd be like he would love that. he never does the same for me. I honestly feel like I'm not being appreciated enough. he always chooses gaming over me too. And won't do things I want to do... I always do what he wants to do because in my mind I'm like i get to spend time with him. I feel like it's not fair. I've tried to talk to him about it. he always says shit about how I'm wrong and that's not how it is. but it is. anyway, i started a new job 3 weeks ago. I saw a guy there and thought he was very attractive. I found out his name was Collin. so the past couple weeks we both exchanged smiles and waves but haven't actually talked. he seems very sweet and nice. he's a bigger guy and I was talking to a buddy at work and he asked what my type is and I said I like bigger guys I won't date anyone that's skinny. And somehow collin heard about that and said to my buddy, "how much weight do i have to gain to get her to talk to me?" idk why but i got kinda like butterflies about it. I know if I wasn't dating anyone right now I would definitely be interested in this guy at work. I love my boyfriend and would never ever cheat but i dont know if I should stay in my realtionship especially if I feel like I'm not appreciated and taken for granted... I'm also afraid like what if I break up with my boyfriend and try whatever this is with this new guy what if it doesn't work out and I missed out on a real future with my current boyfriend... I need some advice. anything at all will be appreciated.