Carbonation experiment

so I overcarbed the beer. i used 126g of dextroze for 2.55 volumes, but used 20 litres of beer instead of the final volume of 19litres... I need a kegging system.
So heres my actual results:
Week 1: Creamy head some hop aroma, not jumping out of the glass, similar to Zombie dust, which was undercarbed for style. nice solid pale ale type beer.
Week 2: (ok Thursday) so a few days, good carbonation, slightly tart, maybe getting too bitter, but all in all around the correct level, i would has at a guess m,aybe 2.5-2.55 volumes at this point. Aroma jumps out and smacks you in the face. Girlfriend was mighty surprised...
Saturday around 2 weeks, fully carbed I think? the warmth is good for it, and well as above grossly overcarbed, not gushing or anything, i initially suspected a small infection (this is still a possibility) but I think its just too fizzy and the bitterness fro mther beer is smacking everything, and theres no taste except a harsh tart hops bitterness,  this relaxes a bit when some of the fizz disappears,  I did have 1 or 2 bottle infections by the looks, so maybe I'm getting ahead of myself? Who knows, I'm gonna give it a third week and crack one open. see the final result...
A final question to those out there reading this; what level do you carb at for an IPA style, and if overcarbed what do you do to rectify the situation?
Food for thought. Mountain warrior will be carbed to an estimated 2.5 volumes of co2, and if i do the same thing again it'll be ok, i'll probably get the carbonation correct...