You can't, no matter what you see, hear or read.
your penis will grow 2 inches
Well, you are already twice as big as me, and I'm 18. (Sadly my erect penis is only 2 inches )= ) I'd say you'll grow 2 more inches. That's a good size.
2 inches
im 13 mate and my penis when erect is about 6 inches is ur 1 inch when uve got a erection or normall my penis when normal is about 2 inch so dont worry it may grow
You're normal.. Absolutely normal. The average size of an adult males penis is about 5 inches. Boys grow at different rates, so don't worry about it too much. You still have a lot of years to grow up so don't sweat it.
2-1/2 inches long by 2-12 inches thick
That depends on the definition of "small penis". Average size of the adult penis is 5.1-5.9 inches long with a circumference of 4.85 inches(thats circumference, not diameter). The average size at the beginning of puberty is about 2.4 inches long with adult size reached about 5 years later.
no
If your penis is already 7 inches long at 15 it probaly started growing early on in puberty and may have already finished growing. Howver if it began growing late in puberty it might still have some more growing to do. The average length of an erect adult penis is 6 to 7 inches so even if yours doesn't grow any more it is already a decent length and if it does grow longer penis of 8, 9 and even 10 inches length are not uncommon.
size it again
2 inches
Then you are very, very short.