It might not seem intuitive, but larger container needs less water, not more water. Especially early on. You want the roots to spread and search for water. That little plant still isnt drinking anywhere near 1L of water per day. And unless you have extremely low relative humidity, not nearly that much is evaporating either.
to illustrate my point, If you have a second bag, or even a 5 gallon bucket, fill it up with your dry soil mix. Pick it up and compare it's weight to your plants growbag. It will give you a very clear illustration of how your plant already has ALOT of weight in water that it already has access to.
To confirm that this was the issue, When you harvest this girl, examine the root ball also. I suspect you will find a very small rootmass that didn't come anywhere near filling the container.
Overwaterings by far the most common error new growers make and it really stunts veg growth.
If you're not comfortable letting the pot dry out for days or weeks, definitely use alot of perlite in your next runs mix. You will see a dramatic difference. You probably shouldn't have any less than 30% perlite unless you anticipate to go long periods without watering because of business trips or vacations.
If you have any other beans I would start another one up while this girl finishes. You'll likely find your next plants veg growth to be alot more vigorous now that you have an idea of the process.
Sorry if i came across harsh, not my intention. Just trying to help get you back on track. Good luck!