Ok shipmate, you sound young. You are worrying about nothing I assure you. You are absolutely normal in size. If all things are operational you got it made.
Just a little advice from an old goat. Women are a bit different than we men about sex.
Guys are perfectly content with "quickies" on a regular basis. And they can be fun and exciting when circumstances allow for them for both the male and female. Just not as an everyday experience. Take your time, espicially the first time! Make it an experience not simply an act. Don't immediately try to penetrate her. It will not be as pleasureable for either of you if she is not ready. Read up on errogenous zones. Be attentive to her needs and let her body tell you when she is ready. When excited she will become flush, her lips, nipples, and vulva will engorge. She may have goosebumps. Talk to her, LISTEN to what she has to say!
When you do enter her do not expect to last like the movies I am sure you have seen. AGAIN... ESPECIALLY the FIRST TIME. You will become able to control things better with time. More than likely, you will be like a bottlerocket the first few times. No problem, thats the way it is. Just remember... you have her warmed up and ready. It is not over.
Use your fingers to penetrate and stimulate her while you are flaccid. You are a young guy and will again be hard as a rock in a few minutes. Dont forget you have two hands. Use your free hand to carress her body while you re fingering her. If you take the time to attend to her needs while you are recovering you will get a treat my new found friend! Having just ejaculated, you will last far longer the second time! She will be in high gear and you will be ready to rock!
OH yeah... ESPN will rerun that Sportcenter in a half an hour.
When you are done, don't reach for the remote control. Remember, she is different from you. It took her awhile to get going, and it takes awhile to cool back down too. Hold her, kiss, softly drag your fingertips along her ribs or the back of her arms. TALK SOME MORE. Offer to run the bath water... jump in with her and soap her up and rinse her off.
Now go see if your favorite football team had a good of a night as you just did!
average Joe