I feel like my erection got smaller?

You've got nothing to worry about. Most likely, the last time you measured you were more hard than this time. To measure just watch a lot of porn without jerking off, and then when your penis is super erect and hard, and its starting to get a little sore, that would be a good time to measure, because it'd be at its fullest. Then you can masturbate if you feel the need to haha. Hope this helps.

No smoking - no beer/ale - no booze - no drugs. ANY of these can interrupt blood flow to your penis resulting in diminished libido & cause erectile dysfunction or impotence. Stress, anxiety, depression, fatigue, crappy diet, lack of exercise, & some medications can also cause malfunction at the junction. People who get enough sleep (about 7-9 hours a night) are more likely to have higher productivity, feel more energetic throughout the day, and experience less stress? Sleep is crucial for concentration, memory formation, and repairing and rejuvenating the cells of the body. Both mentally and physically, a good night's sleep is essential for your health and your energy.

@Brian - lol, I was that size when I was 5! (***** please)

@op - It's all in your head man, it used to happen to me. Get a porn movie you really like, wait for it to get the hardest possible and it will be at you max.! It didn't get smaller, that isn't possible. And 6.5 is more than enough to make a woman scream your name lol ;) Enjoy bro!

Stop worrying about your wiener. It is what it is.