You've proved that cheap credit enabled the demand to be converted into sales. You haven't proved that cheap credit drives up house prices.
The demand was already there; the cheap credit simply facilitated it; the market set the prices.
Under a buyer's market, prices tend to
drop because the vendors are now competing with each other for sales, while the buyer can pick and choose. And that's exactly what we're seeing right now. The cheap credit merely perpetuates the market; it does not raise or lower the prices.
Do you seriously think that everyone started putting their house prices up because they thought to themselves "Well, people are more likely to afford my house now, so I'll jack up the price"?
Prices rise under a vendor's market, which is created when supply is outstripped by demand. The scarcity of houses allows vendors to keep their prices artificially high, because they know there are fewer alternative properties available.
This is not what we're seeing at the moment.