I hope some can help me with my tax question with previous...

I hope some can help me with my tax question with previous experience rather than a general advice.
I received my commsec summary for year 2015-16. It shows Total Buy $85,000 and total sell $67,000. The list is made up of 30 transactions.

When my accountant was doing the tax return, he said I am more of share trader and he treated my trading style as a business. Therefore, he was saying my loss is about $-18,000 (i.e. 85000-67000 = 18000).

Is this correct a correct way?

Because I did not lose 18000 as some individual stocks are on "hold" status. My actual loss is about $2000 as I record all my transactions in the Excel.

The question is why they only look at Total Buy and Total Sell and their difference?