Working for a mentioned comapny as a boot fitter.....
I would put you ina decent pair of kids boots. The thinking is that they will fit your feet, and a Decent quality pair will fit. Something like the Scarpa mowgli, or the Meindl magic junior are top notch quality boots. Best thing to do is get your feet measured, weighted and unweighted, then see what they say!
Had this problem t'other day with a young lady wanting mountaineering boots. It was nigh impossible to find a pair, and this was talking to manufacturers!
Half_viking.