Desperately TTC

Johanna
Hi everybody 😊
Totally new to all this ! 
I'm 34, have 2 children from previous marriage and during marriage I was sterilised. After marriage broke up, I got back together with my childhood sweetheart ! 
He didn't have any children, and longed for a baby. I had a sterilisation reversal 2 months ago and we have been trying ever since ! 
Unfortunately, my partner works away for 12 weeks at a time and also has low sperm count 😔
Been using CB digital ovulation test but only seemed to have a positive result for a few hours..
Feeling really disheartened 😔
Has anybody else experienced a short 'fertile' window ?Â