Ohhh boy.
First off welcome.
This is more of a question for "Safety & Training", but it does fit here too.
Stalling (aerodynamic stall) isn't really an issue for what you're asking. While it is a function of canopy size, it's not really what you should be worrying about (intentionally stalling a canopy is a normal drill and is something you should have familiarity with by the time you get licensed).
Canopy size is more about speed and responsiveness.
A larger 'student sized' canopy is analogous to a large family sedan. Slow, not terribly precise in handling, but predictable and easy to control, especially for beginners.
Small canopies are similar to sports cars or race cars. Very fast, very responsive, very precise handling. But potentially lethal in the hands of the inexperienced or untrained operator.
The typical metric is "wing loading". Weight of the jumper (weight is the total weight of the fully geared up jumper) in comparison to the size of the canopy. Because of the prominence of the US in the sport, weight is in pounds and size is in square feet.
The standard recommendation for newly licensed jumpers is less than one pound per square foot. Students generally go lower.
That's why, at 180 lbs (probably around 215 fully geared), you are under a canopy much larger.
Different DZs have different policies on what kind of wingloading students should have. Most allow higher (smaller canopy) as the student progresses.
Some DZs have limited student gear, so your size choice may be limited.
Where I started (a small club DZ), all the student gear was 288 Mantas.
So, at ~150lbs, I was loading that canopy very lightly.
The last DZ I jumped at had a much wider variety of student gear, from 265 down to 170 (the 170 was more for rental to licensed jumpers, but was used for very small students who had nearly reached licensed status).
At this point, I wouldn't worry about what size canopy they are giving you.
Work on consistent landing patterns, approaches, accuracy and flaring at the right height.
Larger canopies are more forgiving, and it's ALWAYS better to err on the side of caution.