Hi Jaisy,
You say "Lets start with that and go from there"

I'm afraid you've completely misjudged the starting point.
The starting point isn't getting everyone else to tell you what to choose.
The starting point is you learning about what choices are available and then working out what is suitable for you by asking for help & advice based upon what you've learned.

What research have you done?

You say you've been thinking about it for a while and that you've decided it has to be perfect and undetectable.
Is that as far as your thinking has led you?
That doesn't really help you narrow down your choices.
Its not like there is a 'detectable' range and a 'non-detectable' range, just as you're not going find many people for whom detectability ISN'T an issue.
Each type of system has its pros & cons.
The reason there is so much choice is because the idea is to replicate an individual's natural hair with a replacement and everyone is individual, so their requirements are an amalgamation of different specifications.
Detectability & perfection come down to the wearer and the choices they make, how skilled an attachment they have and what style they choose to wear their hair.
Its not about being able to say "this is a non detectable hair system that will look perfect, so buy that".
Someone else's idea of perfection might not be yours.
Its all about making the right choices that will suit you, your needs and your lifestyle.
If it were a simple case of you asking what you should order and someone being able to just tell you, there wouldn't be over 145 pages of forum posts.

So if you really are worried about detectability and perfection, like most things, it will be up to you to do as much research as possible and understand the subject matter.
Remember, it will be going on YOUR head and become part of YOUR daily life and it will be only YOU that has to deal with any consequences.
So really YOU should be the one doing the research so that when you do get advice, you understand what is being advised and said and then you can filter that information to tailor your own needs.

Unfortunately no-one can walk you through the entire thing from start to finish and the people who get the best advice (and subsequent success) are the ones that have gathered information and are just seeking clarity on certain issues.

So check out the different systems available. read the pros & cons, look up different attachment methods and generally just get to understand the basics and as much of the terminology as you can.
Then when you get answers that speak of 'density', 'ventilation', 'graduated hairlines', 'front contours' you will have an idea what people are talking about.

Good Luck