Cavity is the way to go off 20 and with a changing swing. They will give you the forgiveness for the bad days and still help you come down to a figure where a c/f option may be better suited. At your level I have to be honest and say an off the shelf brand would help. The only thing your pro might need to advise on would be the flex but at your age I'm pretty certain a bog standard off the shlef regular would do the trick. Get your swing working regularly, get cut and reassess