They look like they are doing just fine. As far as yield goes, it is very hard to estimate that. It depends on the strains, lighting, and how good the overall growing conditions have been. The light is the #1 factor. If you use cheap lighting or not enough light your yields will suffer. Rough estimates for different kinds of lighting go as follows(gotta be looking at the wattage the lights draw from the wall): HPS: 0.5g-1.0g/watt, cheap Blurple leds: 0.5g-1.0g/watt, CMH: 0.9-1.8g/watt, High-end leds: 1g-2g/w. Now those are rough estimates and you can definitely hit above or below those. It seems like you are using a blurple led, so you want to either look up the light online or find the label with all the power info on it to see how many watts it actually draws. The reason you go off what it draws and not what it is advertised as it because sellers always lie about the wattage when they advertise those kinds of leds. They will say its a 600w light when it only draws 120w. Hell, I've seen lights advertised as 2000w leds but only draw 300w. So once you find that out multiply the wattage by 0.5-1 to find a rough estimate of your yield. If all your plants completely fill the grow space once flowered you shouldn't have much of a problem hitting 0.5g/watt.