You are limited in the size of your batches, but BIAB is fine for smaller batches. If you can get another small kettle, you can mash your grains in one, and then sparge by dunking the bag of grains into the other to rinse the sugars. Then combine the two for the boil.
If you really only have a single 2L kettle, then you can still do what you are doing, but mash some grains in a bag before adding extract. That's partial mash, or PM brewing.