remove those rules and add this one and you'll have the desired effect;
(paste in terminal)
/ interface bridge filter add chain=forward in-interface=!ether1 out-interface=!ether1 action=drop
The logic of that rule is as follows:
If packet is neither entering ether1 (i.e wlan1) nor exiting ether1 (i.e wlan2) then drop.
It wont affect traffic that either enters ether1 (from the internet to one of the wlans) or exits ether1 (to the internet from one of the wlans).
Does this work for you?