I am the mother of twins also.  My girls are 25, my how time flies.  I was a little older than you when I had them.  I was 22.  They are my best friends.  You are so blessed, if you have any questions I think I have successfully passed the mothering of multiples with flying colors so ask away! It is a lot of work, but honestly now when others have a baby I always chuckle and say to myself, "oh, you people who choose to have your babies one at a time are so silly!"  If you are going to have kids go ahead and have enough to make it worth your time. 
