For the sake of keeping things moving I'll take a stab at trying to help.

@ 2 weeks I'd say yes they need bigger pots, plastic is easier to work with than pottery clay.

As they should not yet really need nutes, yet they look like yellowing from nitrogen defficiency, and you don't seem to be watching PH, I'd guess starting to lock out, PH may be low, acidic. You have pete soil, also acidic. Get a handle on the PH, Milwaukee has a yellow digital pen thing for like 20 bucks. General Hydroponics has a "kit" with up down and drops to test.

Curling leaves and yellow could also be over water, but soil looks dry on surface. The above two thing are a safe place to start.