Welcome to the board; glad to have you join us.

I must admit that your growth on the sides is pretty thin, and if that is actually two or more months you've got there, I don't know that it will ever look "filled in".  I'm not sure how old you are, I would guess early 20s, so you may have some more significant hair development yet to come, but for the time being a full beard might not look super full at this stage.  I also struggle with growing a full looking beard, so have worn a van dyke for while now - nothing wrong with that.  I would recommend letting the mustache get longer too.  I don't want to discourage you from experimenting, but I think that maybe the van dyke is the best option for you right now.  Having said that, if you want to see how the cheeks look if you give them more time, by all means do so.  Keep us updated.