Need some feedback for autoflower

Hello my first grow in tent I have 4 autoflower plants I don't know their strian I run with bio buzz soil mix super soil with 600 led light 18 light on / 6 light off i give them 4 times nutes with week 6 i have been late feeding. I make lst for 2 plants and one plant start budding sooner so I didn't lst it but now this plant not grow big as before just make the budds bigger. Other plant have yellow bottom leaves and soil is big and take around 1 week to dry when I water it. I think they are fine the big ones old maybe 8 weeks or 7 I used to give them 2 times nutes (mix flora) and one time plain water. One big air fan. I need some help if guys could help me thank you.