Plant short and very bushy

Just the Pheno most likely my guy...you're in week 3 so in another week or so she's going to hit her stretch.

Genetics. BTW, seedlings do not need "humidity domes".

Could be light, could be genetics. She is in good colour, dont see any big troubles, just let her grow, when she will reach pot verge, then they put highest gear, you almost can see as she grows every minute if all goes well. 1 and second week of flower will add more size. Dont panic, love her, some small and chubby brings more bud than tall and lanky. Fact. Enjoy !

Hi buddy its not the light its just how alot of autos start dont worry autos will have a massive burst of growth around the first few weeks of flower a few weeks away yet they can stay small for a while but most end up big by the end just keep doing what your doing dont worry she looks really healthy :) best of luck for a nice harvest have any more questions my dms are always open :) peacedd out buddy