It sounds to me like education is the better option for you, but don't think that by not doing social work that you won't be making a huge difference to kids who need you, you are just unlikely to have to deal with the absolute worst cases of child abuse etc up close. Sometimes it is hard to let things go when you are a teacher too. I have seen plenty of my colleagues burn out because they care too much. There are lots of children who really need their teachers to be a strong and supportive person for them because they don't have anyone at home who fills that role. Students who you don't suspend no matter how badly behaved they are because you know they are beaten when they are at home, students whose mum ran off with the internet boyfriend and left them with their teenage sibling as a guardian. Students who cut themselves and attempt suicide, and use drugs and behave it incredibly stupid and risky ways. There are lots of them out there. You will still need to find a way of letting it all go when you leave for the day, even if it is just because the kids in your class were really naughty.

I am not trying to put you off, some days are fantastic! I just want to point out that as a teacher you really are a social worker too, so you can help kids the way you want without it being an all day everyday attack on the heart strings.