I doubt they are “stunted” - I grew an auto that flowered at 16 days old and 4.5 inches tall. I couldn’t believe it! She stretched out to 20 inches - doesn’t sound like much but she just produced a nice 2 ounces, not bad for a shortie.
I grew her under a Mars TS1000. It’s not a bad light for one (maybe two?) plants. I would suggest getting the Photone app - I’m going to refer you to a thread about DLI, which really helped me get my tiny girl going. Using DLI
Good luck with your grow! Remember Autos have a mind of their own.