Good work on publishing for the first time! It's pretty amazing of you! I'll try my best to make this review as helpful as possible.
-The cover/banner: The cover and banner give off starkly different vibes. You might want to fix that.
-How hooking the prologue is: The very first line of the first chapter has a mistake. I thought it was a stylistic choice but you never use it again. That will leave a pretty bad impression on readers.
Further, some sentences are very awkward with regard to your word choice. Their meanings are unclear and their grammar is incorrect. Take this one, for example.
But when I glanced up, catching his eyes watching me – these beautiful eyes – I completely forgot about my entire hands. Like – I forgot what they were supposed to be for.
The style tells us what kind of person Nik is with the use of em dashes. But the odd word choice takes a couple of re-reads to understand what you were conveying.
The first chapter, honestly, feels like a simple romance story with some dark elements at the end. I would suggest making it more snappy so that people can know what exactly to expect from the story.
-Impressions on the first few chapters: The first chapters are off to a good start. While the characters are surely well made and interesting, sometimes they feel very artificial. A more concerning issue that I should point out is that Nik and Kaami are very timid around each other for me to believe they have been together for 8 years. This last bit is a tad concerning, especially since they are adopting a kid together.
While we are on the topic of characters. The interactions could be a bit better. For example in episode three where Cheryl describes Tau's original foster situation. It all moved too fast to properly understand what was happening and how the characters in the scene were feeling.
-General story and/or artwork: The story is very engaging and unique. It's unlike anything I have ever read.
-Style, tone, and setting: The setting is very intriguing much like the story is clearly one of the strong points of your writing.
I would strongly suggest leaving lines after each dialogue instead of continuing them next to each other.
-Writing/storytelling style and how smooth it is: As mentioned before, some sentences are written awkwardly and the grammar is a bit loose. Both there make the writing a bit rough to go through. You mentioned that English isn't your first language so I would highly suggest using a text editor like Grammarly.
I really enjoyed reading this and learned a lot for myself as well. All the best with your first work. Keep going!