Your fish should not have a sunken belly/ or pinched belly, and also should not look like they are bloated. some where in between. you can play a bit with it but sounds like you are doing just fine, except i would feed morning and evening if feeding two times, and if only one time at night is fine. I would also skip one day per week where not food is given, if you feel you have fed a little too much.Keep us posted on your feeding routine. if it is working for you keep it up. ultimately it is always better to feed as ofter as possible but small amounts. since most of us cannot do that its either one time or two times a day or every other day etc. so when you find what works for you share with others. it will not be the same for all.