Hello and welcome to the forum. I have to say from the outset that I have no experience of giant breed dogs. I have heard that protein should be restricted in young dogs to prevent acceleration of bone growth which may be harmful to joint development. However, that is just anecdotal so I don't know whether it is scientifically correct or not.
I have just looked at your chosen food - Arden Grange Puppy
and the formula is here:Chicken, (chicken meat meal 30%, fresh chicken 5%), rice 19%, maize, refined chicken oil, beet pulp, chicken digest, krill, minerals, yeast, whole dried egg, whole linseed, prebiotic FOS, prebiotic MOS, glucosamine (370mg/kg), MSM (370mg/kg), chondroitin (260mg/kg), yucca extract, cranberries, nucleotides.
Analysis: Crude Protein 26%, Fat Content 16%, Crude Ash 7%, Crude Fibres 2.5%, Calcium 1.4%, Phosphorous 0.95%, Omega-3 0.84%, Omega-6 2.92%.
The review on the Dog Food Directory is here
and it scores a respectable 3.5 out of 5. The two red ingredients are chicken digest
Personally I would avoid maize if possible, especially in a young dog. Also, the rice is probably white although that is an assumption because if it was brown, I would imagine they would say so. Brown rice is thought to be better then white. There are far worse products than this and with budget taken into account, perhaps it would be worth trying a smallish bag to see how puppy takes to it. You will know after a short while if it suits her.
As Tinyplanets says, the filters on the Dog Food Directory are very useful for selecting a suitable product. We can give you further advice on that if you are not sure how to use it. However, there are plenty of threads on the forum where I have described the process so maybe have a look at those.