Is this your Runtz auto? I'm going to assume it is as it's the only diary you have. They're 5+ inches at 3 weeks and that's perfectly normal - in fact, a very GOOD height! I find it very frustrating/concerning at the very beginning of a grow because I, too, think they should be a foot or more taller than they are... What I've done for myself is to keep a log of each grow that records the height at different stages (you can even be as anal as I am and record the height every day!) ... that way, when I get worried about how well a plant is growing, I can go back and look at other grows to see what THEY were like at the same age.... it's all very reassuring!
I will disagree with my growmie here on the one plant that has those weird yellow markings... this is NOT a sign of a sick plant - that is simple genetics - and they are very young leaves, she may grow out of it but I certainly wouldn't worry about it! Often you'll see either strange coloring or strange growth patterns in really young leaves - and neither are cause for concern. And you have definitely done the right thing in starting these ladies in the pots they will finish in... autos don't like to be transplanted as it is usually far too stressful for them... but this is also a reason why you might think they are too small - they ARE small in relation to the size pot - but that's just perception - if they were in a 1L, they'd be huge! No - you've done the right thing and everything is looking very good... You might consider starting them on some nutes right about now - but only start with 1/4-1/2 strength... they'll grow and stretch and soon you'll be wondering what you were so worried about!
Good luck!