Bohai sea is far too shallow to be used for SSBN patrols. Yellow sea too.It's unclear if JL-2A is currently in service. However, it should join service soon enough if that hasn't happened yet.
Bohai is 11000 km from Northeast and 8400 to 10000 km from west coast.
Yellow/ECS are somewhere in between.
the edge of SCS is 10000 to 12000 km from west coast.
As far as China is concerned, 12000 km is probably global range. I think JL-2A is probably designed around that.
If China want's to have a real global range for their SSBN force ( having all the US in range ) they need to have both missiles with 13-14 000 km range ( launched from SCS ) and relativly exclusive acess to the SCS.