Sounds like a sorcerer using sorcery points. Even a Sorlock - using sorcery points to boost eldritch blast.
If you want unlimited spell casting but limit it to cantrips you’ll have to make a lot of utility. You would have to focus on cc, perhaps denial of area, or even small AoE.
The reason why cantrips are unlimited in use is because they are generally for role play or like fire bolt, a basic free attack.
I see you want dice breakdown, but as soon as you make cantrips deal dmg, a person will find the strongest cantrip and use that all the time.
Either look at warlock class Eldritch invocations - there is a reason they get little spell slots, it makes them have powers to cast at will like a cantrip, including fly and levitate and detect magic among others.
Cantrip ms could scale based on level, then look at eldritch blast as example.
This is my feedback on your Spellslinger idea. Might take a while to balance it.
Don’t forget that Eldritch Blast is charisma based, not wisdom, and like that there are several cantrips based on other things then Wisdom, this might be where the Spellslinger has balanced downsides, as Eldritch blast for example is strong when used by a warlock/ high charisma character. So you might deal less dmg while the higher levels provide multiple hits at reduced dmg.
You should probably look at features for lvl 6, 11, etc. To upgrade some cantrips.
Be warned that cantrips only severely reduces cc options because hold person/ sleep and others become unavailable. How to compensate that?
If spell slots is your thing to circumvent you might consider the optional rule of spell points.
https://youtube.com/shorts/oKItfcknwHk?si=cb_96J1m2d6kt-wb