I would have to also add to the solids making no difference to relux here for my DD.

I haven't throughly read all posts but at almost 4 months has you DD's swallowing reflex changed?

If not you could try to put things in your DD's mouth that she'll spit right back out.

DS2 took ages to get this side of it even at almost 6 months old, we would end up in the biggest messes with hardly any food being swallowed at all.