Expectations and reality are not always the best of friends. Being a new mother is very hard. Your body has changed in drastic and probably not so flattering ways, your time is not your own anymore, and your baby has constant demands that you cannot always fulfill. You must have a lot of patience with yourself. and be as kind to yourself as you can, eat well, rest, go for walks. Your energy is limited and you must think very hard about what you're priorities are and what you have time and energy to do. You will have to put someone else's needs before your own more than you ever have in your life. Don't expect to have the kind of social life that you used to have for a long time. You need a lot of help and support from friends and family and you need to be very realistic about what your life is like now.
But don't worry, those beautiful moments will come. They will come when you least expect them and when you need them the most. Your baby will smile at you, or amaze you by learning how to use his/her fingers, or roll over. Have fun with your baby. Dress him/her up nicely. Get out of the house but don't think you can go have a quiet lunch with friends like you used to. Realize that the baby will make constant demands on you outside of the house also. There is nothing wrong with getting dressed at 2 in the afternoon if that is what you need to do that day but the earlier you can get dressed the better you will feel about yourself. Don't worry, you're clothes will fit again soon enough if you nurse, eat healthy, and try to get out and walk with the baby or do some other kind of exercise when you can. The most important thing to remember is patience, patience, patience.