Well, I bet the reason why she doesn't like her mash is because it's 'mashed' in the blender
My birds would not eat that, either! Why don't you try cooking grains al dente [a bit soft on the outside but still hard inside] and adding frozen veggies to it without putting everything in the blender? Try things like oat groats, kamut, wheat kernels, hulled barley, red or black rice [I would not use brown rice as it has arsenic] and lentils [but cook the lentils with high temperature until they are completely soft] - look for Bob's Red Mill products in your regular supermarket [http://www.bobsredmill.com/shop/grains-beans-seeds.html?infinite=true&]. Cook with A LOT of water and drain after it's done so as to remove all the extra water and, once this mixture cools off, add frozen veggies [still frozen so as to retain the maximum nutrition in them!] like chopped broccoli, peas, carrots, sweet corn, diced butternut squash and some cooked [boiled, baked or nuked] sweet potatoes in smallish chunks - mix some flax and sesame seed to it and voila - a wonderful gloop for her! I bet she likes that!
As to stepping up and down and flight recall... you are expecting too much, too soon and from a bird that is not yet at an age to train properly. Children don't go to school when they are toddlers for a reason - namely, because they don't listen and all they want to do all day long is play, eat or sleep. This is the time for you to bond with her, not to train her. She is too young for it and, if you insist, it will end up backfiring on you. Besides, you can't expect a cockatiel to learn the same as, say, a Senegal or a Brownhead like Michael's parrots. It won't happen. Pois are companion parrots and cockatiels are aviary birds - they have completely different natures and interest. BUT, if you don't free feed seeds, you can use them to coax her to your hand and she will gladly do it BUT she might also just fly away once she eats it [they are pretty smart!
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I wasn't going to mention this because although it's not your fault at all, it might make you feel bad but I can't keep quiet about it because this is something you will have to take into consideration for the future in terms of her behavior when adult - it broke my heart when I read that she had been taken from her parents when she was only one week old! Poor, poor baby and what a completely heartless AND ignorant thing to do! No, that breeder does not only NOT care about her birds, she is also quite uninformed about birds (read about filial and sexual imprinting and you'll see what I mean] and a person like that has no business breeding them.