Can I brew espresso with 14g portafilter basket? Being a complete novice, I've been struggling to brew something that looks like proper espresso.
My machine (Ascaso Dream PID) came with 14 gram portafilter basket (58mm in diameter). Several sources have told me that I really should dose according to the dose label on my basket - no more than +/- 1 gram. I have tried to brew with 14 grams of coffee, but have failed miserably:

My shots always run too fast and the taste is pretty light and sour (underextracted?).
I have pushed my grinder (Baratza Sette 270Wi) to the smallest possible grind-size, but it's still too fast. Though at these smallest sizes it's getting pretty tricky to keep the water running evenly through the pack. Again, various sources have told me that I shouldn't go too fine with my grind. The manual of my grinder suggests starting with grind setting 7E for espresso. At that setting with 14 grams of coffee I'm getting a 30g shot in 16 seconds.
I have experimented with various ways of getting my tamping as consistent and level as possible. My current tamping process as follows: knock the portafilter several times against table to level off the initial pile of grains, spin the leveling tool, press down firmly with tamper.
I have fiddled a bit around with pressure. Haven't gone out of the 8..11 bar range. As expected I get a little longer shots with 8 bar. Mostly I've tried to settle to using 9.5 bars.
Haven't yet tried changing water temperature - it's been 93 degrees C.
I've tried with a 2 second pre-infusion and without. Not much of a difference.
It's worth mentioning that my timings are measured from pulling the lever - but it takes at least 5 seconds for the first drips to appear (about 9 seconds with pre-infusion).
Also worth mentioning is that I'm getting lots of variation from shot to shot with exactly the same settings. Like 31g shot in 22 seconds, and then 34g shot in 17 seconds. This seems to happen more when I go to these finer grind sizes. I suspect uneven extraction.
I have also used 3 different types of coffee beans. No real difference.

With the smallest possible grind size, 8 bar pressure and 15g coffee I've managed to get 31g shot in 27 seconds. But it tasted very underextracted.
The best results I've had have been when I've increased dose to 17..18 grams. Then I'm able to also use courser grinds. With these doses I'm finally getting some more crema and the taste is no more watery. Though my basket is pretty-much overflowing at such a large dose.
Most of the espresso-making tutorials I've seen always tend to deal with 18 gram or larger baskets.
So, is there hope in brewing espresso with 14 gram basket (and what should I change)?
Or should I get myself a 18 gram basket and move on (my portafilter seems to have enough room to put a larger basket in).
Turned out that the problem was in my grinder which failed to grind fine enough. After reading the online grinder manual (which unfortunately wasn't included with the grinder itself) I discovered the following section:

After the first few pounds of coffee, the grind produced at the lowest setting may not be fine enough for espresso. To shift the grind range finer, a small washer (included) can be installed below the cone burr.

After installing the extra washer, all my problems went away.