1 week post germ with very slow growth (indoor aut...

If the soil isn't drying well maybe you did gave too much water ... maybe , so next time be easy on watering. Now if you transplant your new soil will absorb a part of your actual soil moisture so it could be a food thing to transplant . Concerning the pot size , well size up or down will require a good water managment , both of them will not like the over or under watering.

When growing autos u need to start them in there final container. Cuz there on a schedule and if u transplant they need time to recover. So that time recovering it could be growing. So yes report ASAP to final container. And use I recommend root trapper II grow bags. Cuz when watering it doesn't come out sides like smart pots but smart pot will do. Also when using fabric pot it helps the soil breath alot better and it's hard to overwater in them. So size up to final container. Bigger healthier roots bigger fruit(buds)

I'm gonna say temps likely had a lot to do with it. Cold temps will just straight up stunt plants. That pot also isnt too big for the seedling. In fact, with autos, you generally want to start in the final pot to reduce stress. Transplanting will stress the plant and stunt it for 2-3 days. Does the 1L container have drainage holes in the bottom of it? if not then that is likely another reason why the plant is stunted. Don't bother transplanting with the plants this young. Doing so would be a good way to kill them. Might I also suggest ditching the miracle grow soil and getting something better? Miracle grow is known to be terrible to use when growing weed as the nutes in it are generally time release and can screw with things when you are trying to figure out why your plant isn't healthy. Go to a local garden/hydro shop and grab a good bag of soil for when you transplant to the bigger pots.