Hi Thank you for asking HCM. I have gone through your query. Your problem is most likely psychological. If you get erections while sleeping then you are not having any organic problems. You should get rid off stress and anxiety as those can be a cause also. When you have enough foreplay with your partner you will get a normal erection.If not getting in such situation then you can approach a psychiatrist for antidepressants or phosphpdiesterase inhibitors like sildenafil. You should have a proper exercise and nutritious food. Sea foods dairy products etc can be taken as aphrodisiac. Regarding size: only 2 and half inches in vagina is the sensitive part. So you don t need to have a long penis to satisfy your woman. You can shave your pubic hair which will give you confidence about your size. Hope this may help you. Let me know if you have any further queries.