Amali, firstly, don't feel bad if you may have gotten a bum steer. You did the right thing looking for support and advice and you got your babies fed
I would also strongly suggest talking to an ABA counsellor and/or an LC. There's probably no reason you can't breastfeed this baby if that's what you want. Sometimes one of the 'tricks' is just getting the right advice and support.
You mention 12 weeks - that's a common time when mothers misinterpret changes in their baby's behaviour or feeding habits as a drop in milk supply. Babies are often very distracted at this age and may become 'fussy' feeders, pulling on and off as though upset and frustrated. Sometimes they hardly want to feed at all during the day but will suddenly start demanding a lot of feeds at night. It's a very hard time and it is not surprising that many mothers feel there must be something wrong with their milk, especially if they've heard stories from other mums saying the same thing or if their doctors tell them so.

At any rate, you don't have to make a firm decision till you're holding your baby. I hope things fall into place for you this time