due date confusion

Emma

hi.. I have extremely long cycles average 56days. We had been TTC 9 months and with my long cycles my doctor had sent a referral to gynaecology for investigation... Anyhow I got my +OPK CD46 2nd May.. I got BFP yesterday 11DPO.. Question how pregnant am I? lol. How is due date worked out as my LMP was so long ago? TIA xx