I have a 110 lbs weight set that I recently bought. A couple of months ago (laugh all you want), I could barely do 3 curls with a 30lb dumbell. Now I can do at lest 15. My bicepts obviously haven't gotten any bigger.

I recently went up to 36lbs which I can only do 3 of in good form. The rest (I always do 10 in a set), I use my other arm to get it up a little and let my arm do the rest of the work.

When I do these workouts I feel sore as hell and as the weeks go by, I notice almost no improvement.

Someone please tell me how to increase the size of my bis and tris with dumbells. This is all I have to work with for now. Maybe my diet sucks?