Node spacing is a bit tight, but hard to be certain with this picture.. it's tough to assess in general forma snapshot. something that evolves over time.
soil? soil growing is generally slower growth, which means smaller plants with autoflowers.
You'll still have 3-4 weeks of solid vege growth from the point you recognized preflowers on the plant. Preflowers are the single calyx that forms near each branch.
you definitely don't need a 5-gallon pot for an autoflower. 3-gallons will be sufficient. This too might help. The plant was probably trying extra hard to colonize the large volume of medium with roots and possibly neglecting above ground growth.
Definitely stick to a good wet-dry cycle. you water to saturation, wait for top layer to dry and repeat. If you were waiting for 1" deep to dry, try 1/2" deep next time. Don't try to treat it like foie gras. you use the volume necessary, you wait for appropriate dryback.. irrigating is a reaction to observable facts and not a top-down choice. You cannot over or under water adhering to these simple rules.
Work on your nutrient balance based on what you see.. so far so good.. plant is healthy. whether it is too much or not will become apparent with time. again, simply take notes and adjust for greater long-term health next time. Within a grow or two, if systematic about it, you should be confident in growing healthy plants seed to harvest. There are no magic products that make bigger buds or better plants than their genetics allow.
humidity -- 47% without temperature is mostly useless. VPD is what matters. temp and RH need to be considered together. If VPD was very high or too low, it couldhave contributed to slow growth. VPD is calculated with leaf temps, so if using atmospheric readings, subtract 3-4F when referencing a VPD table. Slightly below 1 kPa is good for seedlings and up to 1.2 kPa for mature vege... you'll see lots of slightly different suggestions in this regard. Even 1.5kPa should be manageable... but you get up closer to 1.8-2.0 kPa and you will eventually stall the plant growth with prolonged exposure.