When stir-frying, having the vegetables be really soft is considerably off-target. The standard is "crisp-tender" -- cooked enough to be no longer raw, but still having some crunch when bitten into. This provides a nice textural contrast.
With more experience, you'll come to have a better idea of how small to cut up the vegetables and how long to cook them to reach that point. Another relevant common technique is, before thickening the sauce, to pop a lid on the wok and simmer briefly by way of steaming the vegetables some.
Another standard of Chinese cuisine in general is in line with your general dietary approach: smaller amounts of meat and larger amounts of vegetables. 2-4 oz of meat per person is usually more than adequate. Enough vegetables to make it filling, and an appropriate amount of starch.
Cooking note
With more experience, you'll come to have a better idea of how small to cut up the vegetables and how long to cook them to reach that point. Another relevant common technique is, before thickening the sauce, to pop a lid on the wok and simmer briefly by way of steaming the vegetables some.
Another standard of Chinese cuisine in general is in line with your general dietary approach: smaller amounts of meat and larger amounts of vegetables. 2-4 oz of meat per person is usually more than adequate. Enough vegetables to make it filling, and an appropriate amount of starch.