Ok, pretty sure you should only be dosing once a day. It's ok if the ammonia lvl drops down to zero with in a 24hr period. That what you want to see. The BB aren't going to die off before your next dose.
So, continue your once daily dose of ammonia to 4ppm. now, your testing for your nitrites lvl's to drop to zero.
Your lvl's look ok but if:
your readings for nitrite are so high they are off the charts. You can do a water change to try and drop the lvl's down so that they are readable on the test.