wishy-washy caffè frappè
I would also recommend that you find dried coffee by Nescafe - specifically the Greek brand if you can find it.  Depending on where you live it can be hard to find but is totally worth it and for some reason foams better than regular Nescafe.  If you search the internetz you will find that there is a Nescafe with a label written in Greek.  This is the one you want!

Once you have strong enough dried coffee to start with then it is only a matter of ratios with water and the coffee.  Experiment, but two teaspoons sounds like not enough - I'd start with a tablespoon to 3 tablespoons water.  Pour over ice.  Add water after you have mixed it but be careful not to ruin the foam you just created.  Remember the ice will start to melt immediately also making your frappe taste wishy washy so make it stronger from the start.