I have the same OCD as you mate, fear of harming children, it's very hard to deal with especially as we are both the polar opposite of what the OCD likes to make us thing we could be / are going to be etc. My thoughts are that I am going to be inappropriate, especially around kids, so much so that I spent/spend most of my days avoiding situations where I would come into contact with them.
This however is a bad thing, because it makes it worse when I do go out, sometimes, if I'm in close proximity to a kid, I get different levels of panic, like the thoughts will say "I am moving to cause them harm" then sometimes, I think to myself "I am going to cause them harm.." and I carry on moving in their direction. Nothing has ever happened though either because I've just stopped in my tracks and thought "ah, another OCD mind trick" and just ignored it, but there have been times where the kid has moved first, and I have panicked like hell thinking the classic "What if..?" the kid hadn't have moved, would I have done it etc etc..
But then I get home, and whether its an hour later or however long it has taken me to calm down about it, I run the situation through in my mind over and come to the conclusion that although I thought I was beyond the OCD, and moved as if I was going to do something horrible, in reality I probably wasn't.
In stressful situations, the body muscles tense up, and therefore every slight movement gets exaggerated, and seems bigger than what it is, hence me feeling that I'm about to cause harm, when in reality, it's the thoughts making the physical movements larger than what they are.
Now I have a good shrink who as worked with sex offenders, perpetrators, and he has to ram it down my throat on a weekly basis that I don't fit the profile of any of the above, but the OCD makes me doubt it, just like I used to doubt that i'd turned the tap off properly, that the gas fire was off, that I couldn't get AIDS off a toilet seat , kissing, cutting myself on fences the list goes on, the topics vary but the DOUBTS and the WHAT IF's which link all those topics mean one thing- It's all OCD.
Don't avoid situations where there are kids as it re-inforces the the OCD which could turn into you having phobic responses like I do, I'd rather be trapped in a lift with a load of Man U fans than be in the city centre surrounded by kids, but I know I have to get out there and do whats called exposure therapy, so I get used to situations and relax in them, rather than getting stressed & tense which just brings on the irrational thoughts.
if you ever want to compare notes or anything, feel free to PM or email me.
hope this has helped ?
take care