Replying to Boot size questions(x-wave8.0)

I am 18 wiegh about 160 lbs and am about 6 ft tall. last year i had size 28.5 boots but this year at the begining of the season i bought a pair of size 27.5 x-wave 8.0s because they were cheap and i wanted to try a tighter more performance fit. Whenever i ski i get pain on the outside(sides) of my feet which is even worse when standing still it seems(lift lines) When i first got these at the begining of the season i could deal with this pain as it was not so bad and would fade in and out. The last trip i just went on the pain was just to f*ckin much and wouldnt go away even when i unbuckeled the bottom two buckz. I was considering taking them to a bootfitter and gettin then strethched or shaved or what not, or i may just get a new pair in a bigger size. i was just looking to see what some people have to say cuz im sure other peeps have had similar problems. suggestions on a good boot for my size and weight oh yea, and i ski about 50%park 50% pow? does one size make a huge diffrence in performance?, whats better a --.0 or --.5? same shell. what does anyone think?