What is happening to your hair just now is it's response to something that has already happened so all you can do is get as much protein and supplements in to cut down any further loss or thinning.
Most post WLS hair loss is just thinning and breakage, it rarely comes out in clumps so it is best to protect what you have by using good shampoo, supplements and getting it cut.
Try not to brush when wet, use less products and let your hair have a few days off fom styling, heating, products etc now and again.
Kerastase shampoo is highly recommended for thinning hair. It really makes the hair feel hair thicker by penetrating it with keratin. Apart from stimulating your scalp, I can't see how the caffeine shampoo can help the actual hair. Hair is dead, it can't be stimulated but if you get a product like Kerastase which contains keratin, this will actually penetrate the hair, coat it and smooth it, protecting it from breakage.
For anyone on the forum with longer hair, it might be worthwhile investigating getting your hair treated with a Brazilian Blow Dry pre-op. This is a keratin-based treatment which takes about 2 hours and costs £75 - £200 depending on length and how pricey your stylist is.
Your hair is basically sealed in keratin and as long as you use a sodium-free shampoo, it will stay in great condition for about 14weeks. Some people advertise this as a permanant straightening treatment as it greatly reduces the need to use straighteners on your hair. Don't be tempted by the DIY kits available on Ebay etc as they just don't work - the straighteners needed for the initial sealing-in of the keratin are much hotter than household ones.
The good news is that post-op hair loss is temporary and will come back so try not to worry.
Best of luck. x
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