Do you really want/need to have three different networks (192.168.7.0, 192.168.8.0 and 192.168.9.0)?
Right now you have the bridge on the AP on 192.168.8.0 (same as the Br2 on the main router and PC1) and you are evidently routing the bridge connected devices on the AP through ether1 with gateway 192.168.9.1.
From your sketch IOT and PC2 are on 192.168.9.0, while the bridge including the wifi is on 192.168.8.0?