There are definitely squid in those areas so I think maybe you need to change your approach. Tell us a little about the amount of time you are putting in and your technique. How many are fishing with you?
The Kurnell side is probably my preferred spot in the bay. Around Bare Island ( be aware of the bommie) also produces for me.
I'd recommend drifting over anchoring. You should be getting weed on your jigs and snagged a bit otherwise you are not in the zone. I tend to squid with at least 12lb line and leader to minimise losses as the squid don't seem to care.
Any area with a mixture of kelp/weed sand and rock is good. One method to try is to move into an area close in and fan a series of casts towards the shoreline and all around the boat. Change jig try again and if it's not working move. It doesn't have to be a big move just to a new spot. If you start getting them stay there and watch for followers it's always worthwhile having another rod ready or your mate cast at it as you will often get two. If you think you have one don't strike at such but do lift the rod with the aim of the barbs penetrating as often the squid just hold on and let go when they choose. Keep a steady tension on them so they can't easily release themselves so don't pump and wind.
There is no need to have some massive ripping action or going to fast, it's more likely you are going to fast then to slow. Think of how far the rod tip moves and how far the jig moves in the water. A lift and drop often works. Mix it up and see what happens, Make sure you allow enough time for the jig to drop staying in the zone. If you aren't getting snagged occasionally your jig isn't in the zone.
Another method is to go a little wider and drift. You should be able to manage two or three rods doing this. Have an idea what depth you are in and think about where the jig might be in the water column. When doing this I'd usually pick up a rod give it a few twitches drop it back in the holder and do the same with another. You'd be surprised how often it's the unattended rod that picks them up. Over time you will have a pretty good idea if it's weed or squid. Again you should be getting weed on the jigs or snagged occasionally. Put the cheap jig on the unattended rod so it doesn't hurt as much if you lose it.
Change drifts and jigs if it's not working repeat the drift when it does. It's worthwhile to dedicate a whole day to squidding rather than giving up and moving on to fishing. Don't be scared to squid in deeper water if you are not getting into the zone you can use a sea anchor to slow the drift or a small sinker above the jig works well.
I have never squidded off Towra but I don't doubt it would produce.
Welcome to the forum.