i dont mean to sound negative here, but if your daughter is really having that much trouble eating at 12 months old, i would ask them to check for any digestive, swallowing problems or disabilities.
she really should be eating better and be more co-ordinated. (ie - bottle) but dont think that this is in any way a reflection of your parenting, cause its not. your doing an awesome job, and are abviously being very very persistant.
also, feed her infront of them, show them the issues she is having, so they can see first hand.
as for food, try doing a 'mass mash'
nothing added to it, just pure veges and puree meat. white potatoe is great to add weight, and also, sweet potatoe is full of vitamines and minerals. add finely chopped beans, peas, squash (they love it for some reason, kinda sweet tasting) pumpkin and any others you can think of. carrots etc....
boil together, drain well, and roughly mash it.
be careful with boiling her meats and veges with rice to the point of mushy. when foods are overcooked, they tend to lose some of their goodness. try adding it when the rice is already cooked. so the rice goes really soft, but the meat and veges isnt overcooked.
if she continues to have eating issues, with the swallowing and choking side of things, PM me, i have had alot to do with kids with swallowing problems.
good luck and i hope it goes well with the paed