Space opera series war with another group of planets? Not set on earth possibly young adult

[[deleted user]]

I read the first book of the series in the last 5 years (2015-2020) - seemed quite 'new' possibly on kindle/goodreads/another kindle friendly platform. Have not got access to that kindle/account anymore.

Following humans but don't think it was set on earth. Follows a group of young adults trying to make it into an academy or space cadet system.

They end up in teams of 4 per ship.

One had taken his brothers identity I think and was a low level courier doing illegal jobs between cities. One was the daughter of one of the highest raked female officers - but only just scraped through. One was from a farm planet and the last was an infiltrator from the species they were trying to attack.

One of the instructors had been previously injured in a battle and was part of the intelligence unit - who was getting close romantically(?) to the infiltrator - who could swim? longer than normal cadets due to her physiology - even though she looked the same.

Spoiler

The aliens they were fighting against thought that they were attacked first, whilst the people that we're following are told that the aliens attacked first. Some kind of government/military conspiracy

I can't find this book so I can read the rest of the series - it's driving me mad - but I am finding a lot of other content to read whilst looking!

Any help appreciated

[Kris]

OP (original poster) account is deleted. Moving to the "Now we'll never know" folder.

Thanks Becca.