Story of my life! You could have been describing me and Mr. Munchkin to a T.
My best suggestion is to introduce him to your sisters
gradually. We started dating right before I was initiated and our house was small, so he met the 10 of us very quickly (sometimes you need guys to pick up stuff and help out). When I was a counselor, some of the freshmen sisters lived in my hallway, so he knew them before they joined...in fact, he would talk to them during the Rush silence when I couldn't!

Even now, over three years later, he's not as comfortable around my independent friends (whom he met first) than my sisters, but that's not really a big deal.
Also, be patient. I know it's exciting to have a new guy who you want to show off, but you certainly don't want to overwhelm him and make him do stuff he doesn't want to. That's not to say that you should sacrifice your own social life with your sisters out of his discomfort.
Best of luck!