Without seeing what the rest of your units look like I couldn’t say 100% for sure, but I would say one thing to keep in mind is that it’s much better to spread levels over your team rather than pump a few up to max. I see a few max E2s, which (while it will get more people to use your support units) is very inefficient for your exp & LMD for what you get out of it. The general advice is to get everyone in your main team to about E1:50 before getting anyone to E2, and get them to E2:40 or so before pushing anyone further than that. Once you have most of your main team to E2, Mastery levels become more important than getting more operators to E2.
As far as team building goes, I generally see this advised until you get a hang of what can be swapped out:
2 Vanguards (usually DP skill types)
2 Medics (1 ST and one AoE)
2 Snipers (at least one should be anti-air, often 2 are needed)
2 Casters (1 ST and one AoE)
The last slot is flexible depending on the stage’s requirements and personal preference. DP-on-kill Vanguards, Guards and Defenders are pretty common.
Once you’re gotten that down, you can start toying with what’s good for changing around. Here’s my main team, for example–while only the first five are usually “set in stone”, you can see it doesn’t exactly fit that main team composition but have some decent reasons for them.
So you’ll notice I don’t have 2 defenders, 2 snipers, 2 healers, or 2 casters. But I’ve found here that:
Saria is a powerful Healing defender, and her skills can swap her to be either ST or AoE healing depending on the situation. So in most cases I don’t need a second Medic, allowing another DPS to be added.
Estelle is an AoE guard, which blocks 3 at E2 just like a Defender. She can be used well on lanes that have a lot of weaker enemies, so that they die before doing enough damage that it doesn’t matter that her defense is lower than a Defender’s. On maps with a lot of stronger enemies though, I do have to swap her out with a true Defender like Hoshiguma.
I don’t have two Casters, but I have a Caster and two Supporters that deal Arts damage, which serve the same purpose. They do less damage than a true Caster, but each have separate utility that can come in handy.
I don’t have two Snipers, but frankly Eyjafjalla tends to melt anything that approaches her. As long as I have her a Blue Poison covering different areas, I usually don’t have to worry about any drones slipping by. On drone-heavy maps, I usually use an Exusiai from a friend support.
You’ll also note I do have a few maxed operators, but my entire team is at least E2:40, with the exception of Myrtle–since she usually isn’t actually hitting things and is there to print DP, her level isn’t usually that important.