YSK: If your espresso tastes "good", it's not real espresso
The idea that espresso should have a "pleasant" taste is a modern, American concept with no root in traditional preparation.
Espresso, by definition, should imbue an intense bitterness and discomfort without any hint of sweetness or enjoyability. If you find yourself enjoying such taste notes as "chocolately", "caramel", "creamy", "fruity" etc please understand that you are drinking a coffee flavored children's beverage which would be more appropriately served at a Starbuck's drive-thru than a traditional Italian cafe.
In traditional Japanese archery, you train for a long time before you ever actually shoot an arrow at a target. Stance, breathing, movement. Eventually you get to hold the bow, and it's a while after that before you get to put an arrow to the string, and even then you will not get to loose the arrow at the target until your instructor believes you are ready.
No no one wants to hear this, but drinking the shot is like releasing the arrow. And you are probably not ready for that. The first 6 months should be just setting up the machine and then cleaning it. Focus on your breathing, focus on your posture. Then you can spend a few months grinding beans maybe, but do not try to pack the puck before you are ready and I mean ready. After a year or so, maybe you can start boiling water.
Tasting the shot is something that comes at the end of a long long road. Maybe a hundred shots should go straight into the sink first. Maybe more. Point is, you can't rush this.