have you tried the brauers stomach calm? I use that with Aiden with his reflux. It sounds like you are doing everything right. My paed does not recommending thickening formulas as he says it ended up making it harder for bubs to bring up, therefore being more painfull.
I would see your gp. I was prescribed Losec, but, was recommended to try mylanta first, which i did, cause i hated the idea of putting my 7week old (at the time) baby on prescription medicine. The mylanta worked for a couple of days, helped the reflux, stopped the screaming, but, it then started to upset his belly, i used to be able to hear and feel it gurgling. So, i gave losec. And the change was immediate. But, its up to you if you want to go down the medicated path.
Some people say that babies can feed less when they have reflux, cause they start to associate feeding with pain.
Also try infants friend. Simaler i guess to infacol. I tried a couple of different ones, and i found the infants friend better.
Now, Aiden is mostly fine. he is on solids, which helped, and rarely do i give him losec, and mostly now he is just a happy chucker when he does have the need.