T-square and stellium

Greetings,

If someone could spare some time please to help me understand on the following:

Do I have a T-square involving:
Sun in Libra (8th)
Ascendant in Cap
Moon in Cancer (7th)
?

If yes, what is the best way of working with this energy? Is it the reason why feel frustrated all the time and unable to find my vocation? I have problems sticking to things, mainly jobs and career-wise.

And, do I have a stellium in Scorpio? I had a reading few months ago and the astrologer mentioned it but then I've read online that only planets can form a stellium and mine apparently has the Midheaven it. I'm confused?

How does a stellium manifest anyway?

Sorry lot of questions but I would appreciate help on any of them!

A stellium is just a grouping of planets close together in a particular sign/house. If they are in close conjunction then it is a pretty intense mingling of their energies. For instance, I have Jupiter, Moon, Mars, and Saturn all in Virgo in the 9th house, but only the first three are really close together.
Your stellium consists of Mercury, Venus, Jupiter, Pluto, all in Scorpio along with your North Node and MC. Jupiter and Venus are REALLY close though, so I would get familiar with what these mean in conjunction. Obviously, Scorpio and the tenth house are big players in your chart across the board.
As for the T-square, I'm not sure that the angles "count" as part of this type of configuration. Maybe they do, but I haven't researched it much. The Sun-Moon square is kind of a wide orb, so I normally wouldn't worry about it too much...except that your sun doesn't have a lot of strong aspects, so you may feel it more as a result.
As for having trouble with stick-to-itiveness, that's stereotypically a Gemini trait, which you have on the cusp of your sixth (work) house. Saturn in your second also suggests material rewards are not going to come easy.
I think you need to take stock of what you are passionate about--what really stokes your fire. Your chart indicates massive energy output, if only that energy can be directed properly.