I have been lifting weights for about a year and a half now, and have moved from 3 lb. weights to 5 lb. weights. The 5 lb. weights have been much too easy to lift for several months now (I can do dozens and dozens of reps). The next step up is 10 lbs. but these are too heavy! I cannot even LIFT them to perform the exercises! There doesn't seem to be anything in between. What is a weakling like me to do? :>

Advice and suggestions would be appreciated.