First ... The length and girth (thickness) of your penis is not an issue unless you believe it is. At your age, it is possible that your penis will continue to grow, especially as you begin to use it for sexual activity. ALSO, penises, just like other parts of you, come in as many styles, shapes and sizes as people themselves! I've seen smaller than yours and bigger. You may see other boys who seem to be larger, but everyone is somewhere along the "size" spectrum, and just about all of them function just fine.
So, size is not the point, necessarily, unless you are trying to have intercourse with someone who is very heavy.; in other words, they have a lot to get past in order to push your penis inside. That situation is not very likely, so let's deal with more "routine" sexual matters here. First of all, is it FUNCTIONAL, right? If you can pee through it, if you can masturbate to orgasm and ejaculate (if your body has begun doing that) , if it feels good when you play with it, if it provides you with wonderful sensations, then no worries, you -- and it -- are doing just fine.
THE ABILITY TO GIVE PLEASURE TO OTHERS -- If you are heterosexual, remember that a girl's primary organ for sexual pleasure, the clitoris (which is located at the top of the vulva, nestled between their vaginal lips) is OUTSIDE her body, meaning that your erect penis is certainly capable of pleasuring that part of her (along with your gentle fingers and your tongue, by the way). Rubbing your erect penis along, around or against her clitoris can bring both of you well along to orgasm. Next, her G-SPOT (another major organ for her orgasm) is located just inside the top of her vaginal opening, kind of “behind” her clitoris. If you put your finger in there it feels rough, like the roof of your mouth. Your erect penis is certainly capable of reaching it. During intercourse, try thrusting upward rather than inward. This will force the head of your penis against it and should excite her nicely. And you don't need your penis, necessarily, to stimulate her elsewhere on her body: kissing her mouth, her breasts, nipples, belly button, inside her thighs, nuzzling under her arms, licking her ears, her toes, etc etc etc. – pretty much anywhere!
A lot of that also holds if you are homosexual. Male bodies have similar sensual places that you can stimulate. The same no-penile methods of stimulation are crucial to a complete lovemaking / sexual experience, regardless of gender. And of course, much of homosexual sex centers around oral / genital contact, and very few guys will turn down the chance to give oral sex to someone because they are too small. Too large, maybe, but never too small. So, no worries there at all.