If from what i'm seeing is right, your humidity for veg is way too low and should be up at 50% at least! Young plants, during veg thrive off higher humidities and lower RH (30-40) during flower. They could be bigger but I wouldn't worry so early on. Get your humidity up. Its an auto so putting them in final pots is fine, transplanting them stresses them out too much and they are on a short time scale. Just make sure you're not over watering. Give them another week and report back.