I think my dd could take about 2 tspns (is that about a 5/10ml?) mixed into water to make sloppy at that stage.
I started with baby rice at about 5 months like you with a bit of puree at lunch (11ish) and baby rice with veg at about 5ish. I then moved on to pure veg /carb mix about 2 weeks later and then introduced some protein by 6 months. DD is now 7.5 months and she's on breakfast porridge with fruit, a protein/veggie mix lunch at 12ish and a carby type tea at 5ish...we're on 3 milk feeds a day. I cooked up some stuff pre going back to work so we're working our way through that at the moment.
As to amounts - she seems to take about 150mls of food at lunch/tea - (only know as there are measuring lines on the tupperware stuff I use - didn't realise they were there when I bought them ) - which is about 10 15ml tablespoons of food (or one of those icecube thingies).