J.M.
Wow! I'm in your exact same shoes and it almost had me in a melt down today with our little guy who is small too (19 lbs at 18 mos). I've had him on the floor picking the food up and he too things its a game. I get it that at this age they all think it's a game but is so hard not to get frustrated, especially with the added pressure of them being small. I keep telling myself that it's just a phase, like all of the previous challenges we have gone through and encourage myself to be patient with him.
Good luck and feel free to e-mail me to chat more about this. I completley know your challenge with the food/low weight pressure.