Should I transplant my girls to bigger pots?

[LeKushChocolat]

The plants in the first picture are 38'' and 36''. In the second picture the girls are 30'' and 29''. All four plants are 3 months and half old. They are sativa dominant and i feel like their growth has slowed down. The lower leafs of the biggest plant are turning yellow. They havent started flowering. They are also on a 18-6 light schedule. They are in 2,6 gallon pots. Thanks for the help

[Campesino]

I certainly would.
I would also recommend training those girls. I hope you are aware of and prepared for the Flowering Stretch.

[Waltermelon]

Christ on a crotch rocket those are going to be insanely tall once they are switched to flower. The normal rule is 1gal for each foot of growth or month vegged.

[Canuck147]

No need to transplant if you don't want to. Few years back, there was a solo-cup challenge on this forum. Many people grew around an ounce of cannabis in solo-cups.
That being said, if you transplant you will slow down their growth a bit. Might confuse the plants if you do. I mean they have their roots spread out in their home, next is flowering. Put them in a bigger home and they'll have to spread more roots.
I'd say you are doing a fine job so far, keep em growing.