I'm also 24, and have stayed at home with our daughter since she was born last summer.
It's kind of a weird feeling, isn't it? I sort of felt like that at first, too, but I also reminded myself that what I was doing was so good for the baby, staying home with her. I also was relieved to have a break from regular work, to be honest.
Your baby is still really young, though. At this point I think everyone understands if you don't put make up on every day, or if your hair is in a quick pony tail instead of done up. As time goes on I think you just get a better at the whole thing. Eventually I just started taking like 2 minutes on SOME days to just throw on some make up, and to get out of yoga pants and to put on jeans. Now, that's not to say I even do that everyday NOW. Being a sahm gives you that freedom that when you get back to work some day, you are going to miss. If you spend all day at home with a baby, you should be comfy. And some days I still get out of PJs, only to put on different loungey clothes. Other days I get up, put on regular clothes, and do my make up a little bit. It's all a matter of what I plan on doing that day, how I feel, and what is going on.
I think it's good you realize this now though. Maybe you can start just with one day, getting up and taking a few minutes to just do something that makes you feel back to being you again, not just mom. Anything really. It's so hard at that point though because everything is about baby, it seems.
Just know that it gets easier as they get a little older. I still can't wear much jewelry since she drools and chews it still, and has broken several necklaces when I tried. But other than that, you get more of a chance to be normal. You have a few minutes to get ready in the morning a little. You can enjoy a glass of wine at night when they are in bed. You can take them out more easily as they get older too without hauling everything with you and enjoy lunch with your friends, or dinner with your husband.
It really does get easier. I can't explain it. Sometimes still i get into little mini-ruts like that, where a week or so will go by and I just feel a little stir crazy or frumpy or whatever, but as soon as you realize it you just do something about it. it's hard to explain. One thing at a time, do little things here and there, and you will get outta your rut soon enough. =)