Penis will never get shortened, of course during cold in winter it may look shrunken but regains its size during erection. You are too anxious about this and hence not getting full erection. Just relax; everything seems to be okay with you. Stop thinking and discussing about it with your girl friend. There is no substance on this earth, which can increase the size of your penis. All available products are making money for their manufacturers because of male’s anxiety and worry about the size of penis!