This is 5.5 weeks, and the plant beside it is 11 days. No nutes for the first 4 weeks, using Cannazym and a basic flower fert at half strength now, and the small plant is just tap water. Try not to get caught up in thinking it's all about nutes and all that, as you can grow perfectly fine without them, and fail a grow with them depending on variables, or vice versa. It's usually not the nutes or lack of that causes issues, it's normally pests, pH, microbe balance, light, humidity, temps, bacterial or fungal infections under the soil or a combination of all.
These are literally in $4 potting mix, under cheap eBay lights and in terrible humidity and temps due to location and are still turning out well...however I've seen and grown plants under 3x the light, perfect environment and constant attention and end up half the size.
There is a large amount of genetics and luck involved, try not to be too hard on yourself, as a lot of the times.yku can do your best and still suffer.