Could you still be pregnant if you just started the pill for 5 days but forgot it 3 of those days and had unprotected sex and decided to quit taking it and have breakthro bleeding or a light sopttting?

There's a fair chance of being pregnant the thing with the pill is it takes 14 days to take affect properly and skipping 3 out 5 days wouldn't have protected you from anything. My suggestion is visit you doc or get a home test. It's the only way to be 100%