Marci, don't be so hard on yourself, really! Layla is going through her adjustment period of being back to her normal schedule. She was spoiled being with you and your parents for almost a month-she had all of you to herself, and didn't have to share any attention with any other dogs. Also, she didn't have any dog friends as companions while you were on vacation. Now that she's back to her usual schedule, she's got to learn to share the human attention, to be away from you, and to play nice with her friends. It will take a few days, but after she readjusts, it will all be fine. I'm actually glad to hear that Layla's standing up for herself and letting the bigger dogs know that she doesn't want to play rough. Also, she may have just been re-establishing order with her friend Oaklee.
Emma and Milli have gone to the same daycare since Emma was about 6 months old, and I had never had a problem. Do you remember my post about how they started marking there? Well, it's because I didn't take them as frequently (since we have our house/yard now), and they were unfamiliar with their surroundings and their dog friends that they used to play with every day. We left them there overnight the weekend between Christmas and New Years to go to a wedding, and they wore their go fetch panties-but they only needed them on the first few hours they were there. Once they remembered where they were, and who the other dogs were, they calmed down and were fine the rest of the weekend.
Also, BOTH of mine snap and growl a little at the others when they first get there. It's one of their only ways of communicating-if they could talk and work things out, they would
They just need to put each other in their places, and after a time or two, they have it all worked out between them, and they're the best of friends! Don't go and pick her up if she's having a bad day-that will only reinforce that you will "rescue" her if she's acting up-which could lead to her acting up more. Leave her there for her normal amount of time, and she'll learn to get along just like she did before.
Don't worry-it will be fine in a day or two!!! Hang in there!