hey guys, thanks for your advise i knew it it was my boot. bcoz i can feel my feet moving around to much. but my bindings are large to xlarge from size 9/14 i think should be fine. one more thing if i buy 10.5 boot do i still need to get wide deck? & how about the size? i'm 5'10/120 lbs. should i get from 150 to 154?
Try on all the boots you can, and don't go by what your normal shoe size is. You might even find something smaller than a 10.5 is the right fit. Your toes should comfortably be just about touching the front of the toe box, or as close as you comfortably can. I wear size 10 running shoes, but I fit a size 9 Burton boot, and I just barely find 8.5 Salomons uncomfortable (and only on one foot). Also remember that after several days of use, the liners will pack out about a quarter size, so if your boot is loose now, it will just get looser later.
If you do end up with a 10.5, it's sort of the gray area between standard width and wide boards. Every board, every binding, and ever boot is different, so there's really no definitive answer for you as it also depends on how wide your stance is and what your binding angles are. If you have a very wide stance and very ducked bindings, you can ride a regular width board even if you wear size 12 boots. Lots of variables. Bring your boots and bindings with you when you go board shopping (unless you know the store carries exactly what you ride), so you can try to line up a proper fit.
A regular width board will be quicker/easier to turn from edge to edge as there is obviously less space between edges. Conversely, a wider board gives you a larger, more stable platform for landing jumps or riding deep powder. If you can get away with using a standard width board, I'd go that route as you'll have a lot more options, particularly if you're looking for a shorter deck. I don't see many 150W boards out there... :P