Nice story, would benefit from a beta reader if one could be found (although there are many fanfiction works with much worse English).
'sltrips' -> 'strips'
'room mate' -> 'roommate'
'Severus head him off' -> 'Severus headed him off'
'Harry realized there was it was a bit too tight for his present size' -> 'Harry realized that it was a bit too tight for his present size'
'It tied to swipe her finger' -> 'It tried to swipe her finger'
'I don’t Kit to just wander around' -> 'I don’t want Kit to just wander around'
'slid the door owider' -> 'slid the door over'(?), 'wider'(?)
'I miss you to' -> 'I miss you too'
'she found the older girl’s antics to be amusing' -> '_he_ found the older girl’s antics to be amusing'