Oh yeah, I did forget you asked for playstyle advice too…
While it’ll vary depending on the map–especially the later on you go–the general advice is 2 vanguards, 2 defenders, 2 snipers, 2 casters, 2 medics (1 ST and 1 AoE–I don’t see any AoEs for you though if Perfumer is off the screen she’s a good beginner one), 1 guard and 1 to change around depending on the map.
It looks to me like you’ve been following that so far, so some advice for switching things around to expand your playstyle options:
Defenders can often be swapped out for a 2- or 3-block Guard–especially AoE guards like Specter. This works best when the spot you’re putting them in gets a high volume of weaker enemies, so they can kill things faster so you don’t leak just because of sheer numbers. Silverash can also hold most lines that don’t have heavy, high-damage enemies, especially if you have him at E1 with his second skill on (though you’ll probably never use it again once you have his S3).
A high leveled Healing Defender (I don’t see any on your list, but Gummy, Nearl and Saria are the prime examples) can sometimes hold a line without needing a Medic to back them up, giving you room for more DPS. Edit: Cardigan can sometimes do this, but you have to be extra careful since her skill has a relatively long cooldown for a self-heal.
That “1 guard” spot can often be filled with a DP-on-kill Vanguard, like Vigna. Like guards they tend to be very high damage, and since you get all the DP back when you retreat them they make great assassins, especially early in a stage (I’m looking at you, 4-7…)
As some side advice, once you get stuck on any story missions, I would make it a priority to farm materials to get as many operators promoted as you use on any regular basis. The second skill and trait that operators get on the first promotion is usually what makes that individual unique compared to others of their archetype, and so before then you’ll only get a feel for what that archetype is rather than that specific operator. While it might slow down your story progression a little bit in the short term, it’ll give you a lot more options to play around with when you’re having difficulty somewhere.