Faucet Water Pressure
You should disassemble the kitchen faucet and inspect the temp/flow control valve assembly for debris/obstructions. It is common for debris to get knocked loose and flow downstream, causing problems like this. Your manipulation of the pressure regulator could have done it. 

Another consideration: those bathroom faucets appear to be older and may not be of the "water saving" variety. The kitchen faucet seems new/modern and likely has water saving flow restriction, either the sort described by @Ed Beal or integral to the design of the flow control valve.