It looks pretty good. That soil looks like its powering that plant ok. Look at a bag of Dry Fertilizer ( 5-5-5 / 4-4-4 or similar ) .
Many good brands to use ( veg and bloom ) :
Example :
Roots organic VEG / BLOOM
With this one … simple. 1 heaping tablespoon in a gallon of water … mix well and water in. DONE.
DTE 4-4-4 ( general purpose )
You can use it start to finish - 5-5-5 also good.
Simple - a heaping tablespoon or so - work it into topsoil - water in . DONE.
HAPPY FROG ( veg / bloom )
Same as above - Tablespoon or so / water in.
Recipe 420 ( a personal favorite of mine )
A very good and complete dry fertilizer ( veg and bloom ) - Tablespoon on topsoil ( work it in ) and water.
Dr. Earth
Another excellent fertilizer ( most nurseries carry it )
Dr. Earth has another “ Flower Girl “ for bloom stage.
You can
also just TOPDRESS more of that soil you are using and water in. By doing that you are recharging what the plant already consumed from that potted soil. AND … plant is already accustomed to it .
Lastly , do not fall for the hype about buying fancy bottles of this and that. It’s a big waste of money.
GL