I also wouldnt try and force the bird to eat. But do encourage it! Some babies eat well and other dont. I suppose it is also survival of the fittest.
I do agree with the comment about water in the formula. When I hand reared mine I kept worrying about water but I was told she didnt need any water because there was already water in the formula. However mine ate very well so i havent had to face that issue. I specifically chose her because she was feeding so much better than the others. When they are hungry they should call for food.
I couldnt tell you how much mine ate a day - I fed her 3 times a day from the age of 3 weeks and gradually slowed it down to 2 feeds a day and then just one before completely stopping. As soon as her crop was full she would stop eating voluntarily. I would say by about 10 weeks I had stopped the formula. Remember if you keep giving them formula they will keep eating it forever. you have to wean them off it.
Another trick I was taught is to wet their seed for them just a little bit. At that young age they are too young to know how to crack seed properly and wetting it just a bit softens it and helps them to get it open. Obviously dont let it stand there for too long as it will go yukky! But if it is in an open bowl that they can reach easily at least it gives them a chance to start. They are never too young to be introduced to seed and fruit in my opinion. They may not be able to eat it but they get used to having it there and as they develop they can start trying.
I also see no reason to not give her apple. it is soft and easy for her to pick at and start learning how to eat it. Even if you chop small pieces up or mash it for her. Another thing I gave mine (and this sounds gross I know!) was white chicken meat. and also veg like peas and corn. Because it was soft she learned how to pick it up with her feet and nibble on it and was soon eating. She still to this day LOVES chicken and meat of all kinds! ha ha!
Are you feeding her with a spoon or syringe? I used a plain teaspoon but like I said mine ate well. The people I got her from used a teaspoon that had the edges curled up to form a funnel to accurately direct the formula into the baby's mouth.
Your other option is to phone the breeder and ask how the bird was feeding before you got it and see if they can suggest anything.
Wiht regards to bonding you need to have her with you at every possible moment. Talk to her, touch her a little bit if she allows it and feed her things she likes. I find my bird is willing to try ANYTHING i am eating. I cant emphasise regular handling enough thought, it's the most important thing. Also do some research on "bluffing" before she reaches this stage. When I got mine I hand reared her right and she went aggressive overnight and I had no idea why. she drew blood if i tried to move her! But i researched it and persevered with her and never let myself be afriad if her and she soon realised her bluffing was just bluffing and wasnt getting the desired reaction. If it's summer she will soon molt as well and mine gets very crabby. the breeder told me it is like them having a mild case of flu and they feel horrible. Mine was molting and hitting bluffing stages all in one right in the middle of breeding season and she was a nightmare! But i stuck with it, took the bites as they came and never reacted badly! At one stage she slept on top of the curtain railing for 2 full days because my fiance and i were both too scared to take her down because she would pin her eyes and attack! They get over it if held regularly and treated with love and kindness. Mine still sleeps out some nights. I started putting her away after she got hold of the TV wires and the sofa but generally she roams the house as she will and takes control of the dogs (eats out their food bowls!) and just loves beingw ith us.
Yours will too - lots of attention, talking to, bathing or spraying her down when it's hot (mine loves a good hose down!) treats and handling - you cant go wrong. Every day must be her day. never leave her for a full day without holding her and letting her out with you. I have often gone away and had someone look after her but they dont let her out because they are scared (???) and when I come back it takes her a while to relax.
ok im going to shut up now! im hogging the thread! lol! If i find any extra feeding info i will post ti for you
:D my breeder asked me the other day if i'd like to hand rear some of he's babies till they are weaned 
make the formula a bit tastier, i use a jar of baby food and mix the formula into it with water still. When they get ready to fledge they cut down on the food. Try putting corn kernels and things like peas and other soft foods in for the bub to play around with and it will eventually get the taste for it.