I was going to say couchmanagers, but I think they only go to 14 teams also. However, I did a little bit of digging and it looks like
My Fantasy League does have some 16-teamers going from time to time. Not sure if they're free, and you might have to wait to get the format you want and have it be 16 teams, but it looks like your best shot. Otherwise you might just have to go off 14-team information and extrapolate a bit - there might be another site out there that would let you do this, but I sure can't find it on a first glance ...