Oh love it's ok. You don't have to justify your appearance to them but you need to do it for you. Concentrate on what you can change now. Try a new shampoo, when I did my training we were told to not be loyal to a brand as its good to change. Put some concealer on and whatever else makes you happy, for me it's lipstick :)
Wear something you are comfortable in, not what you think you should be wearing. I lived in pyjamas for a year after having dd and only changed to go out after a shower.
See a doctor over your medical problems and start the ball rolling on that.
Is money an issue? If not then please treat yourself to something, anything that will cheer you up. I love buying perfume, always makes me feel brilliant.
Back to you, I mean this when I say that I wouldn't want to be friends with people who looked down at me, you will meet new friends soon enough and they will like you for you, not based on what you look like and I think the changes you need should be just for your own self esteem.
I've had pnd with my ds, 15 years ago and it's so easy to neglect ourselves isn't it? Take back a little bit of control and start with baby steps, you absolutely will feel better in time.
Baby groups by their nature can be quite judgey. It's human nature. Many people will probably have been worrying about their own appearances but I totally undestand why you posted.
You are important. Remember that!
You have been brave to post and I think you start feeling better soon 