if the bike is too large for you, it will make it pretty hard to balance right. but if you can pop it up in the air around 40 degrees or so doesn't seem like the frame is the problem, perhaps your fear of leaning back while going forward?
on the frame topic, if it is longer then you will have more weight on the forward half of the bike simply because you are laying flatter along the top tube. if it is shorter than you can raise the seat higher and your body shape gives the center of gravity an easier starting point to lift up the front wheel and lean back.