Same age as this, and it was under 100w the first four weeks, and 160w now. Sucks how much a stunt can effect a plant.
I had an auto I left outside in the cold last year that did the same thing, stunted at week three and started flowering after 5 weeks. At least I got a good 3 weeks before it straight stopped. Ended up being a 2ft dick nugget that somehow that got me 40g. Ended up being a 15 week plant for 40g lol. The plant beside it ended up pulling 270g in the same timespan, but keep in mind it was a photo vegged for the same timeframe. I had no idea what I was doing to begin with hence an auto outside in autumn lol...our "winter" averages 47°F nights and 70°F days, so not too cold, but at that time in late autumn we had some 38f nights and 63f days with rain.