As I see it you have a couple of options here. You can make an attempt to sell the gloves to someone else that has a smaller hand than yours and recoup some of your money to purchase a new, larger size than you have now. You other option which I really don't recommend is to just tape your wrists and not wrap your hands. While wraps give your wrist some support its usually not that much and many guys have to wrap their wrists with tape a little bit before wrapping their hands. Wraps really support and protect your hand more than your wrist. Also I have to wonder if maybe you have a cheap set of gloves like the thin, cowhide, bag gloves. Those are not really for use on heavy bags and the impact of using them on one will bother some people's wrists. I realize they sometimes sell them with heavy bags but they are not really adequate for heavy bag workouts and anyone that can hit with any kind of power even if you wrap your hands and tape your wrists. A set of bag gloves will run you about $50.00.
As the tittle says, I have 180' handwraps and i cant fit them in my gloves,but i can fit my hands without them perfectly...i tried training without hand wraps but my wrists started hurting...and i can't get bigger gloves atm
also sorry for my poor English :P