V.: First off - YOU GO GIRL! You sound so much like me and it actually overwhelmed me to read what you wrote. I thought I was the only one trying to carry the world and do it all by myself.
Slow down! You will still be in control of everything but you have to give in a little.
Your little one is feeling your stress and the fact that she will sit on the potty and/or knows when she needs to go while wearing pullups, etc., is telling you to let her be. She can do it and you know it but right now the problem is that it isn't fitting into your busy schedule of moving, working for your boss who is ill, handling all the affairs at home, with your other child, etc., etc., Whew. Even you need to step back and that is what she is showing you. You already know she was potty trained and her daycare is telling you she goes and sits. Let that part go. Is there anyone else who can help with the meeting situation either taking your son or picking him up so you can get other things done at that time, or is it a must be there "mom" thing? Start leaning on your friends and immediate family. You may be in the same boat I am but if your husband is not working right now - is there any reason he cannot take your son or spend more time with you getting your affairs under control?
I know I know - it is a hell of a lot easier to do it yourself (that is what I always say) but you will boil over. So before that happens - allow yourself to find just who you can count on. You will be very surprised.
Stay strong but your little one is fine. Let her be and she will respond. Give her that extra hug and kiss and tell her you know she can go potty when she is ready. In the meantime, the pullups work fine for everyone.
T.