Will protein make me slower?

So the other day I went out and bought 2 bags of GNC's "Amplified Extreme Wheybolic 60" because the man who worked there told me it is the best stuff for what I am trying to achieve. I am the 2nd fastest player on my football team running a 4.5 only as a Sophomore and I run Track & Field and on Varsity as a, according to my Coach, State qualifier in the open 100M, 200M and 4x2 and 4x1 because of how fast I am. Problem is though, I need to get bigger for football according to my Coach. He said I have everything he is looking for in a starting Defensive Back this upcoming year, except for size. He told me get bigger, and I will potentially start my first year on Varsity. But what I am wondering is if this Protein I got will make me slower? I have heard that some people who take Protein gain a lot more mass and lose speed, and I am wondering, if this Protein will make me slower? And if so, by how much? Or will it make me faster? All this I am kind of worried about because I do not want to get slower. Will any of this happen?