Tanner is eating well, and actually gained a couple of more ounces this week. He is at 15 lbs 6oz. This is fine with me at the moment.
He is looking better and acting better and eating better than before. I've decided to hold off on the ultrasound. I'll take him back to the vet in May to check his red cell count then, and if still low, will discuss having the ultrasound done. If improving then I'll do nothing more than wait. This seems to be in line with what I am seeing, and if I didn't know he was anemic, I would not suspect anything was wrong with him, based on outward appearances, appetite, and activity level.