Lourdes,
I don't mean to sound uncaring or non-compassionate, but you absolutely should not be discounting your services. You have set fees for a reason - this is business. You cannot go in to a restaurant and ask them to discount their menu items or go ask for a discount when you have your oil changed. You can't ask your OB to give you a discount on your ultrasounds or bloodwork. I know it may feel personal, but you need to remain professional and explain that your fees are set and you're understanding of their situation, but you're not in a position to give away your services at discounted rates.
Also, you're pregnant - you need to be taking care of yourself and keep the stress to a minimum. Chasing 6 kids around is not going to be easy so don't add any more stress to your lifestyle.
As far as returning to work, I think that's your call. I'm able to take 8 weeks of maternity leave (though all unpaid) and then I'll have to use a daycare when I return to work. I've offered to work a few Saturdays that are lacking coverage in September, but I should be 4-5 weeks postpartum by then. I thought about returning to work earlier for the paycheck, but this is my first child so I want time at home to get the hang of things. I think you have to decide what will work best for you and whether or not it means changes in how you run things with your childcare services.
Good Luck!
Carrie