No need to worry too much, my first baby's "yellow" last for 2 month and keep check it every week in the mother child health clinic. My son is now near 3 years old, I didn't see any "yellow" effect on him.Keep check it is very safe.
For my 2nd baby, he also went to hospital to do blood testing for once and I heard the doctor adviced the mother to keep breast feed the baby but don't each food for helping blood circulation as it may slow down the "yellow" release.
Both of my babies are feeded by breast milk + milk powder in the first month ( but very little around 5 oz per day and last for 10 days) then only breast milk till 8 month ( 1st baby) and now( 2nd baby).