Why is my bike looking so light yet so cheap as I make a list of what I need to build it?
I'd be careful with a random carbon fiber frame from the internet, since you don't know how well its built (and frame failure can lead to serious injury). We've discussed this at length multiple times on this stack exchange, so you can search it. There are also a lot of fakes of major manufacturer bikes online, so you should be wary of those too, especially high end carbon fiber ones. It's very easy to make two bikes that look identical from carbon fiber, but one is much less safe than the other. Read this article for an example of the horrors (including for other fake bicycle products). 

Personally, I'd rather buy a bike from a major manufacturer which I know was built correctly at the same price point even if its components aren't Ultegra and it isn't carbon fiber. 

Also, its hard to know how well the bike will fit, versus just trying a bike out at the shop and getting a better idea of fit. This takes quite a bit of experience (and is pretty inexact too; you may hate something that fits on paper).

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I'll assume the groupset follows what Chain Reaction Cycles is selling at the moment: Front and Rear rim brakes, front and rear derailleur, brifters, crankset, cassette, bottom bracket and a chain. 

It's not clear from the product page that your wheelset has a 11 speed compatible freehub, so if it doesn't have a 11 speed compatible freehub, you need a different wheelset. 

You're still missing tires, tubes, seatpost, saddle, headset, pedals, stem, cables + cable housing, drop bar tape.

You'll also need some tools to work on the bike (a torque wrench is critical on carbon fiber), some of which you may want to leave to a shop (e.g. a headset press).  And other ancillaries like appropriate greases and stuff for working with carbon fiber, of course.