Not necessarily.. I had it the other way around (2 bridesmaids, 3 groomsmen) because my cousin who was the 3rd bridesmaid found out she was pregnant and there were some complications, so she didn't want to be in the wedding party and I didn't want to replace her. The pictures still looked great and everything was perfect.. so don't worry about it too much. Congrats! Enjoy your wedding.
EDIT: Just have the guys standing at the front and the girls walking in on their own.. And to walk out, you can have two bridesmaids with one groomsmen, and the maid of honor and best man walk together.