I think at this point your parents will probably cut you a lot of slack in terms of what activities you do and how frazzled you seem at the end of the day.
You might want to look at some options such as hiring a neighbour teen to help out. It is amazing the little things they can do like get you things or put stuff away or entertain the kids or be the one sitting by the sandbox making sure the toddler doesn't eat the sand while you relax in a chair and feed the baby. Since it is the summer and kids are out of school it should be easy to find someone interested in a bit of extra money and since they are never left alone with the daycare kids age wouldn't be a factor and younger say 12-14 year olds that are not old enough for conventional jobs should come cheaper - and don't forget you can claim the cost as a deduction once your daycare is open again.
You might find having the girl around that actually talks and takes some of the pressure off of you helps a lot in terms of how you feel. You may also find that being so busy with two kids of your own plus the daycare helps to take your mind off things and you feel better about everything. But at the same time you now know the symptoms and can seek medical care sooner before things get out of control and that will help too.
All the best as the final weeks pass and you meet your new baby.