Changed my mohawk about 2 days ago

i never blog so i dont really care how this turns out. but i had originally got my hair cut at a barbers and they completely did what i told them not to so i have resorted to self styling. i had originally had for about 3 months a mohawk that i called the "MoFauxHawk" because the idiots who cut it cut my like long hair to about 2 or 3 inches and i have a mohawk that was faux because it was too damn short. my hair also at that time was about 1/2" on the sides (clipped or buzzed whatever you wanna call it) and the top was all one length of about 2 or 3 inches. the back was about 3/4" due to my previous hairstyle and i would always cut the back short and have the top long. anyways. i decided to attempt to cut my mofauxhawk into a true mohawk. i went to my girlfriends and had her buzz or clip or whatever the top. so i left about 3" of hair across that goes down the center of my head. both sides of the stripe have been clipped down to 1/2" (i dont like mine any shorter than 1/2") and the center is like 4 or something inches. problem is the back is still stupidly short. and also my mohawk is not centered. my right side has about an extra 1/2" to it. im just afraid ill mess up and then ill keep going back and forth till i got no hair left. but i want it to be equal on both sides. i also have to fix up the back (have my sister or girlfriend do it). but whats the best way to make sure the front is centered well and even on both sides.ill also post this in the forums cause i might get some hits there. and i use ICE spiker glue and GOT2BGLUED hairspray (actually i never use the spray cause that glue keeps it held incredibly and its water resistant).