Congratulations!! He is very pretty! He looks like a typical curious boa. What ever you feed him, you don't want it to leave a noticeable lump. So long as you can't see it, you are good. But if a small rat doesn't leave a lump, I'd stick with those, not back down to something smaller. I'd get him back on a 2 week schedule by the time he's 2, as well, if you plan to change to 10 days.