Wow, this realy gets to to reader. The scene at the MoM is detailed and yet vague enough to let it stand as it is or to expand it later as recap or flashback, really exemplary. Little Harry's entry into the world of wonders (an own bed, all you can eat, and last but not least magic) takes good care of world-sight and the priorities of an five-year-old.
Will 'Uncle Harry' also save others beyond Sirius, maybe Lunas mother?
It's up to you to continue or not, but I hope You will write more.