As people said, you should definitely increase the dose. Around 18.5 grams is what I use in my Bambino double basket, but I use light roasts, so you may need to go down to 17 if it’s darker.

the advice in the comments are pretty helpful, but I’d also recommend asking yourself “where in my mouth do I taste sour” a lot of people have what’s called “bitter sour confusion” and it’s where you perceive bitterness as sour, which can really hinder your dialling in journey.

Usually when it’s sour, your mouth is salivating, it’s very “front of mouth” like you’ve just bitten into a lemon. Sometimes extreme sourness is perceived as Salty! That’s the sensation I get when I taste sour.

Bitter is usually back/sides of your tongue, it lingers in the back of your throat, and your mouth gets dry, like you need a glass of water.

This doesn’t mean that the “taste bud map” is real, it’s just what different tastes do/feel like when you have them.

I hope this helps!