Thanks for the detailed post. But I find this too much of work and difficult to spot any errors. Why not use Cointracking Portfolio Manager.

It has

1. Automatic import of trades through APIs.
2. Average purchase and sale price reports.
3. Booked and unbooked profits.
4. Ability to calculate your taxes.
5. Set up price notifications.

I have been using it for three months. It does what you are trying to achieve and much more.