I think if you are not wanting to bfeed anymore then you could completely stop as I wonder how confusing it might be for your breasts to keep bfing when you don't want to and want them to stop producing milk, does that make sense?
Is bub ok with the bottle?
If you have a low supply then your milk production should be easier to lower than if you were making a full supply.
If you still put bub to breast then bub will drink what ever amount and this will be produced in return (ie supply=demand), so it might be harder to reduce and stop milk production with bfing, but of course it can be done.
The way you know if the weaning or reduction in supply is effective is how your breasts feel, if they are comfortable then they are coping with what is happening but if they are uncomfortable/full then they are needing some attention, ie express some milk off for comfort but not to fully soften, as you are doing).
The main things to look out for are signs of blocked ducts which can lead to mastitis again so letting your breasts guide you is probably the safest, and if the pump doesn't remove much milk for you then you could do hand expressing.
I don't think yours is a 'textbook' case of weaning or suppression so it is hard to be prescriptive.
How about ringing the ABA and I would presume you have seen a LC with your complicated bfing experience so could you call the LC for advice?
The links below may help, all the best.http://www.kellymom.com/bf/weaning/http://www.breastfeeding.asn.au/bfinfo/weaning.html