<human>: Give me the gist of the text in a nutshell

So my girlfriend (25) and I (26) are having our one year anniversary next Monday.  Awesome!  It has been the most amazing time and we are completely happy and love each other a ton.  She is my best friend and I couldn't ask for a more perfect person to be in love with.

Yesterday my sister sent me a text asking if my girlfriend would want to watch her kids on Mondays and Tuesdays for a few hours each day (she has summers off).  It sounded great and the only concern that I had leading up to it was that she really wanted to do it and she didn't feel pressured into it.

Well.  She wanted to so she called my sister and called me back.  She's going to do it, awesome.  Mondays at my mom's house, who will be home, and Tuesdays at my dad and stepmom's, who will be there, to swim.

So far we have done the holidays and occasional dinner type thing and that has worked well but now I'm kind of freaking out because she is going to be around my nieces, nephews, mom, dad, stepmom, and sister on a pretty frequent, regular basis.  I don't think there's a whole lot that I can do after the fact so...

Am I being selfish or a baby?  I don't want this to throw off what we have or to really change anything.  What should I do?
<bot>: I have an awesome relationship with my girlfriend and I'm uncomfortable with her suddenly spending a lot of time with my family.  Am I being selfish?