Lord, as much as men thirst after vagina you'd think they would take some time to learn about it. There is nothing great about a dude hitting your cervix aka the back of your vagina. It hurts A LOT. The average vagina is only 6 inches long. Even if you had 12 inches you would only be able to get half of it in. You are upsetting yourself for nothing.
Umm. Not trying troll, but there's a little bit of mis - information that I'm about to correct.
First, the average vagina canal(before arousal) is 4 inches. The maximum length differs between each woman, but when aroused, the vagina can stretch to accommodate genitalia from 5-9 inches without hitting the cervix. Some women have a preference for men who can reach(Not necessarily bang) the cervix, adding a little bit of pain to the sensation of being completely filled. This is where the women that have preferences for 8+ comes from.
As for the OP, there's isn't much that can be said or done. You have to play the card you were dealt. You can...
a. Find a woman that is anatomically similar in size. We're talking women in the smallest 10 percentile in vagina size. Finding one that you're attracted to (or vice versa) will be difficult since your sexual compatibility pool is reduced drastically.
b. Use toys to get your woman off and deal with the fact that you're emasculating yourself.
c. Pay for p*ssy for the rest of you life and not give a fukk what anyone thinks.
d. Just kill yourself and you won't have to deal with having a small penis anymore.
This post should cover every question about penis size.