Tonsils can cause apnea however they are not the only cause. You can not "hear" all apnea not all snoring means you have apnea. The worse case of apnea I have worked with was a 3 year old who the mom laying in the bed next to him said see he didn't snore at all in six hours he had blood oxygen levels in the 70s and about 500 events
A 3 almost 4 I would have them removed. The younger the better.