As you can see from my post I'm a single mom too. I fostered my son before I adopted him. I am also a school teacher so it was easy for me since he was in school when I was working. I have meetings once in awhile after school - when he was in Foster care he had a worker that would hang out with him during my meetings (he was a "special needs" child so he got extra time with workers) now that he's adopted he plays outside the meeting room or he stays in my classroom and watches TV during my meetings.
I get out of school early enough to take him to his appointments - therapy, vision therapy ect. I've had to take off work a couple times for different appointments - but not too much.
Your level of support depends on your agency. County workers don't do much (I was even supervising my son's visits for about 6 months). GOOD agencies will help out with transportation and such as long as it's not every day.
I've thought about leaving teaching a couple times - NOT because I don't like to teach but because I hate the politics of my district - but I realize that if I do I don't think there is any way I can afford to pay someone to help me get my son to or from school or for daycare/camp during his vacations while I'll be working. So instead of quitting, I'm trying to move across the country where the politics aren't as bad as here
I second the idea that you might have to go with an older child. How old is your son? If he's in kinder you could wait for a child in preschool, if he's in 1st you could get one in kinder... If your child is in daycare now I wouldn't think having one more child in the same daycare would be that much harder.
My son wants me to foster/adopt (or biologically) another child because he wants a brother (course he wants one that's his age or older - and no girls) and I keep thinking about it because I know it can't be THAT much harder having two than it is having him back when he had so many issues. But I'm taking a break to give him a chance to settle in a little more (and me a chance to possibly date)