You need to do Policy Based Routing and you have 3 options:
- mwan3 package
- pbr package
- a set of rules/routes for each internet connection.
One remark regarding your configuration is that you still have one network, the 192.168.2.0/24 which spans from .2.0-255
Therefore the additional interface and firewall zone have no use there.
If you really want to separate them, you'll have to have a lan 192.168.2.1/24 and lan1 192.168.3.1/24.