Is a 4" penis too small as my girlfriend thinks it is???

There really isn't any confirmed figure for what constitutes a penis that's "too small".  As with most things in life, it all comes down to personal preference. 

Although some women may think that a 4 inch penis is too small for them, others may think that it's the perfect size.  Unfortunately, we're conditioned to believe that bigger is better in all walks of life, and this isn't always the case. 

Here are some things to note about penis size:

• Studies suggest that most women prefer their partner's penis to be "average size".  This varies by nationality, but is usually around 5 to 6 inches in length.
• Many women believe that girth is more important than length.  It's possible that a 4 inch penis could be more satisfying to a partner than a 7 inch penis if it's thicker.
• It's a bit of a cliche, but it's true in many cases that technique makes a huge difference (pun intended).  If you've got an averaged sized penis but understand how to pleasure your partner, that's obviously better than having a really big penis but not knowing how to use it.

As I mentioned earlier, it really does come down to personal preference.  If your girlfriend thinks your penis is too small, it might be worth asking yourself whether you want to be with her in the long term.

I'd advise that you find someone who appreciates you for who you are, and not someone who criticizes something about your body that you don't have any control over.