Why is my plant not growing at the right rate?

Our female sour diesel is an indoor plant is on Day 20 (26 days ago if sprouted). It’s about 6 inches from foot to tip. I’ve seen pictures of other sour diesel’s the same age, and they were much more developed (they had more leaflets). We don’t use nutrients yet because the cotyledons haven’t fallen off yet. Overall, ours is just under growing and I’m worried ! An thoughts??

Also, our lighting is 45 watts LED multicolor, tonight we are adding a bright white LED 500 watt light

Light at that point would be my guess as the plant grows it needs more light

If we add a 500watt light that is bright white (I guess like 5,000k), would that be sufficient? If we add it in addition to the other light

It’s a possibility good lights are t5 lights ( a type a flourescent) or mh or hps bulbs knowing it’s 500 watts itll probably help it a little more