How many transactions does the 'Transactions' tab on your wallet show?
Do I have to count them manualy?

No. Click on the receive coins tab. Do you have more than one address listed? If so, the rest of your BTE may be stored in one of those addresses. The total you see on the Overview tab is the sum of all BTE stored in your addresses. If you are still interested in selling, PM me. Thanks.
Overview tab: Number of transactions: 551; Balance: 1036.62216526 BTE; Unconfirmed: 0.00 BTE
Receive coins tab: one and only address 8Fyj7FjJ1Fq4wG3VPeJ8Lt7CnSDfUUz2S4
Selling everything for 0.5 BTC