Re: Body sparring.
How are you holding your guard? Are you keeping a high guard to protect the head and chin or are you holding a low guard to protect the body? I'd hope the latter of the two if you are only body sparring.
If you are not doing so now, I'd say hold your elbows fairly close to your rib cage so your arms take the punches more than the ribs, liver and gut when your opponent gets within punching range. You can still hold a pretty good low guard without sacrificing your chin if you keep it tucked in and not out there like a big target.
Make yourself small in the ring. By this I mean bend slightly at the waist so your body is farther away from your opponent and not an upright target.
On a simpler note, hit them first and often. A good offense is sometimes the best defense.