You just got a typical runt imo mate.
How long is she like that
For 1, an 18hrs fem would never show any stigmata like that.
As mouse said. You can still treat it like an auto.
As autos generally work of DLI.
So, if you think she fem. Which i wouldn't say so.
But, by doing this it'll still give the amount of ppf as she would in 18hrs
I only give my autos 13-3.5hrs of flowering at the start of flip. I just make sure they get the right DLI..
Use this calculator to help you get it.
Look at your light manufacturer..
It'll give a ppfd chart. From this you will be able to control ppf by using height and lights % by looking at the tables they should have dif levels at heights/% of power.
Mars have lots of tables for that light ppf.
Here's the cal you can use.
You can use the table from MH and give the DLI according to that.
https://www.waveformlighting.com/horticulture/daily-light-integral-dli-calculator