GREAT NEWS! And what a cutie!!! If the bird is better, then it is not severely deficient in calcium although the diet is really not very good (more on that below). But, the first thing I need to tell you is that your girl is a boy
See the medium size feathers under her tail? The ones that don't reach the end of the tail but cover the beginning of it? Those are called tail undercoverts (or tectrices) and they are green in females and yellow in males so your bird is a male. The yellow on his chest -which shows a lot on both sides of the green V and goes all the way up to his 'armpits' is also a sexual characteristic of males, females have more green and little yellow on their chests.
Now, please no Cheerios or any other kind of human cereal! They are super bad for birds because, as they are made for humans, they have a lot of iron (humans need a lot, especially children) and that is not good for birds. Birds need a maximum of 2% iron, Cheerios have high iron content, some of them all the way up to 45%. The thing with iron is that Nature evolved each species in such a way that they derive all their nutritional needs, at their perfect level, from their natural diets so she did not give the body the ability to get rid of most of the excess. When you feed a bird (or any other animal, including humans) too much iron, it goes to the liver to be stored and as it accumulates, it creates a condition called hemochromatosis which is fatal and has no cure or treatment in birds so, please, stop giving him human cereal immediately.
The other problem with the diet is that you are free-feeding seeds and that is always bad for parrots. Parrots are NOT natural seed eaters (canaries and finches are, for example), they eat plant material like buds, leaves, fruits, flowers, etc. They do eat seeds but they are 'green' seeds -meaning the ones inside the fruit- and they do eat nuts, if there are any in their natural environment, but they never find a constant, rich supply of them. People don't realize that nuts and seeds are not found all year round in the wild, they are seasonal elements because they are the reproductive method of the plant and plants don't bloom and give fruit all the time. So, please, discontinue the practice of filling up her bowl with that mix and leaving it there. You can use the mix as dinner for him (just enough to fill up his crop and a teeny, tiny bit more) but you will need to come up with a healthier breakfast. I feed gloop and that is what I recommend everybody feed their parrots because after over 25 years of doing research on their natural diets and nutrition plus observing what they prefer, I have not yet found a better staple. It has low protein, almost no fat, lots of nutritious veggies and whole grains and, most importantly, high moisture (parrots eat a natural diet that is between 85 and 95% water so anything dried is not good for them) and high fiber (again, parrots in the wild eat a diet very high in fiber as it's all plant material).
Also, are you giving him any supplements like a multivitamin/mineral? Because, going by what you posted he eats, if that was all he has been eating all along, he would be severely deficient in calcium. See, the thing with calcium is that you can give an animal all the calcium in the world but it would not make a difference if the animal does not have Vit D3 which is necessary for the calcium to be absorbed into the body. And no plant material has any -it's produced by the body of animals from a chemical reaction to UV light in the sun. So if he had not had any he would be dead by now which makes me think that you feed him animal protein like egg, meat, etc. You say you give him yogurt which I am sure he likes but it's not really good for him. Birds are not mammals so they don't have the necessary enzymes to digest milk products properly so the yogurt is pretty much going in one way and coming out the other. People talk about probiotics in the yogurt but the commercial yogurts have negligible amounts of good bacteria so it doesn't really work for that - they get their digestive enzymes from ripe fruit and veggies. So, if I were you, I would make sure I am supplementing him with Vit D3 because although he can derive all his calcium (and other minerals) from his diet (broccoli and almonds are high in calcium, for example), he needs the vit D3 (and other minerals in balance with calcium). I use ABBA 2000, a multivitamin/mineral in powder form that I put in their waters three times a week but any good avian supplement will do and I would start him with a daily doses for, at least, 3 weeks in a row and then reduce it to three times a week (because he mostly needs it for the vit D3 as he would get all his other vitamins and minerals from a good diet). I would also highly recommend you give him some non-alcoholic, liquid milk thistle extract to help with his liver because he has been eating too much protein, too much fat and too much iron.
And, please, change his perches. Natural tree branches with the bark on them are the best because that is what they evolved to use all their lives in the wild. Concrete or sand perches and ropes (unless they are made of cotton) are too rough and dowels are the worst possible perch for a bird: too rigid, too smooth, too even. Natural branches have 'give' so, when they alight on them, the impact on their joints is much less than when they do it to a rigid dowel. The bark will help with his nails (wears them down naturally) and the different diameters and positions (don't put all the branches perfectly parallel to the floor) keep their toe, foot and leg muscles toned and the soles of their feet healthy (because the pressure is not always in exactly the same spot as it is with perfectly cylindrical dowels - it is this constant pressure in the same spot that causes bumble foot).