You are in the height of the ants food uptake. Feeding once a week is not enough. I feed every other day. I use J Arthur Bowers john innes no2, probably not as many nutes as fox farm, but at this stage the girls will have drained every bit of nutes from the soil. There is nothing wrong with room temp, imo. Just up the feed rate, not the amount you put in one feed as one feed a week is not enough you need at least 2 or 3 times a week.