That would very much depend on your personality! I've had women place my hands on their breasts, while others "accidentally" left a door open when undressing. Still others have simply taken off their clothes in front of me.
maybe your boyfriend is just showing off to his mates but, if you feel insecure tell him and he should stop showing his friends after all its not his breast !!!!!!!!!
to show your boyfriend your his girlfriend, hang out with him more. Guys get hooked on girls really easily so just hang with him. Do all the fun things you guys like to do together. Buy him little...
If you're talking about what I think you are, you should just wait until the time is right. You may wonder right now how you're supposed to figure out what the right time is; don't worry about it....