I sense in you some of the frustration I felt early on in the learning
process. It's been a year for me and that is not very long. I remember
how powerless it felt staring at shot after shot not only wondering
why the espresso sucked but why it sucked differently every time! Your
problem is... well more precisely.. what is keeping you from
finding your problem is too many variables. Do the following..

BEANS! Don't assume anything. Take people's advice here and get proper
beans. I know you are looking for some light roast but for now just
get something quality and get your extractions working first. I've
found Intelligentsia's Black Cat to be some of the most forgiving
beans around. They ship. Don't assume anything you've used up till
this point is quality. Get some Black Cat or something else shipped to
you that's recommended here and know that that part of the equation is
dealt with.

GRIND! Set your grinder to ultra fine. You have a good grinder so that
is not likely your problem. Dose into your basket using WDT. It's
overkill but it works. What you are trying to do at this point is
remove variables and this works. So grind into your basket with yogurt
cup insert, stir the grounds around a bit, remove the yogurt lid, use
a ruler or the back side of a knife to strike the grinds off the top
of the basket, leveling them off. Don't compress the grinds just
strike the extra grinds straight off.

TAMP! There are varying techniques here but the goal is consistency so
I'll explain what I do. Take your nicely leveled basket and insert it in
PF if you haven't already. Secure the PF in such a way that you can
apply even, downward force without moving or rocking the PF, don't
tamp yet. Place the tamper in the basket using just it's own weight to
lightly compress the grinds. Remove the tamper and tap the side of the
PF with the tamper a couple times to remove excess grinds from the
basket walls. Now place the tamper in the basket again and give it a
single, firm, downward movement. Don't over do it! Firm, nothing crazy
is required. The important thing is that you can repeat a similar pressure next time. Lastly, make sure the lip of the basket is clean.

BREW! Ok now lock in your PF and brew! Did you clog your machine with the ridiculously fine grind? Good! Go back to step one and coarsen the grind ever so slightly then repeat the entire process until things are looking good.

Good luck.

If you get no crema, the cause is most likely stale beans. If you are getting some light crema, then it is time to talk grind/distribution/tamp, but in my experience the only time I have ever seen no crema (i.e. black coffee) is from stale beans. I always have crema from beans I roast myself - even from badly tamped pucks. Seriously, you cannot do anything with stale beans. There is no cure or technique that will recover the fugitive freshness from the past.

Consider the cafe-crema: a coarsely ground and very lightly tamped puck produces a cafe-americano type of cup with a light layer of crema on top (with fresh beans of course). (Disclaimer: I read about the cafe-crema technique from a post on this site and tried it myself, so possibly I am not describing the technique accurately.)

Maybe post a photo of your shot after extraction?

good luck,
don