Ad Sexing: look for preflowers - there could be some signs after 4 weeks of vegging. What is the strain?
They need to get a lot bigger to fill the tent with canopy. Getting more light is probably good solution. For start you can probably put lamp lower to supply more intensity.
I'm not familiar with "600w bloomspect full spectrum" but beware that current practice of sellers is to hide actual watt output, so it can easily be just 250W.. Always look for power consumption, not for sellers' label. Quality of chinese led is also debatable. Read more in forum about it under #led tag.
For example to 4 feet by 2 feet you can easily put 400 watt HPS.