Four weeks should have been fine on the feed.
OF has enough nutrients in it to last the first 3-4 weeks. I also asked how big they were and how many nodes when they sexed, but you didn't answer. Reason being is that I think the
OF, being a hot soil mix, probably stunted your plants, which resulted in the lower yields. Autos have about a 6 week veg period and the key to high yields is getting them as big as possible during that time. Anything that stunts them during that period will lower their yields.
Being that you are using fem seeds, the tiered planting method isn't necessary. That's more for regular seeds. The cups are big enough to get them to sex thereby avoiding the need to commit a 3 gallon pot to what may end up being a male. For your next grow I would suggest you fill your pots with the
OF, then scoop out a couple handfuls in the middle of the pot and replace that with some Light Warrior or Happy Frog, then plant your seed in that. Make the LW or HF at least 6" deep. That will give your seedlings a more suitable mix to start their growth, without the heavy nutrients in the OF. As the seeds grow they will eventually grow into the OF.
When you do start feeding nutes, start at 1/4 strength. See how they like that for a couple feeds, then slowly increase the strength. Most dwarf strains will usually tolerate no more than about 1/2 strength before showing signs of over feeding.
I'd say around 4 weeks is when I gave one a small amount of nutes jus for experiment while I gave the others nothing but distilled water. They were feminised seeds so I wasn't looking to determine sex. I still have plenty of FloraNova for root growth and another for flowering. The first time I used less than the recommended amount and still got nute burn. Should I put even less or get some new nutes from my local hydroponics store?