Turnover as per shipping bill value or as per bank realisation

I file ITR under 44AD and mostly in export business. 

 My question is whether while filling ITR, whether I should file the turnover as per value in shipping bill, since the same is reported in GSTR 1 returns as well.

OR 

The turnover should be as per payment realised in bank. There is always difference, due exchange rate difference.

The ITR form has a column, "Turnover as per GST", in which I will be obviously giving the turnover as per GSTR1 / shipping bill value.

My concern is, if I report Turnover in ITR as per bank realised value, which is usually less, then turnover as per GST, am I inviting scrutiny notice? What is usually the practise?

thanks