Cant get all coolant in

So i drained and flushed the coolant on my 96 2.2L. Poped the radiator petcock, drained that, and also the drain plug on the front of the block. QUite abit drained out, close to the 3 gallons that it supposively holds i would say. However when filling it, it takes a gallon and a half. It took a gallon hard than drained down a bit to fit the other half after like 20 minutes. I have bled the top, steam will come out when hot, eventually fluid. It has been a couple weeks and still not gone down. The temp runs about average, straight up or just past on the temp gauge. Any ideas what gives w/ the not fitting it all in? it doesnt seem like any more air is in there. and if it is how can u get it out.