I just found out today that one of my bridesmaids is dropping out of my wedding

I'm not mad because I completely understand her situation (she's in grad. school and is a TA so she found out she can't cancel a class for the wedding) and I want her to do what's best for her. However, now i don't know what to do about my lopsided wedding party. We have 6 groomsmen (including the best man) and I was already starting off lopsided at 5 BM, and now without one it's 4 on one side and 6 on the other. I don't really have a lot of girlfriends left that I would feel comfortable asking to join (as sad as that sounds). So do I try to find another girl to fill the empty spot, ask one of the groomsmen to step down (I would prefer not to do this because I don't want to be bitchy/mean and I want them all there to support my fiance), or just have it be lopsided? What would you do in this situation??
March 2012 December Siggy Challenge- My Bouquet
160

Invited to Our Disney Wedding!
55

Are ready to party
43

Are missing out
62

Haven't decided yet
RSVP Date 2/9