YANBU - might be worth mentioning you thought her car was cool when you get your keys back from her, and as for wanting to plan so child's room is clean and leaving downstairs until last, seems perfectly reasonable, since you're the one paying, and can have certain requests met.
However, if she has only been with you 3 months, it isn't like a 'bust up' over nothing with someone who has worked for you for 3 years, and it does seem just a way to get a quick exit.
Assume that for whatever reason (travel time, has decided to start some business venture, or just doesn't want to work for you any more) she has chosen to 'move on'.
At least you got some 'reasons' for the decision. When one of my (website design) clients chose to get someone else to rebuild their website (having been with me for years and with no feedback to explain any disatisfaction) I was the last to find out. The website still doesn't look 'complete' (1 year on), the firm they moved to went into administration in May this year, and for all I know, their site might disappear overnight if the web hosting bill fails to be paid.
Will I care? Actually, yes, on a professional level, because I [nearly] queried whether the site was complete, and told them about the administration while also making it clear their website and e-mail might fail under the circumstances, without any warning of it being about to happen.
Of course, it's none of my business, and I am half expecting a "Help!" phone call some day soon, but this is a busy firm of solicitors and while I could just be grateful they have come back to me, and ready to pay me, another part of me says to ignore their call, however much it would hurt my long-term relationship. Oh, yes, what a great "relationship" ! I really have nothing more to lose with them, perhaps...