Constipation during pregnancy

So ever since day 1 of my pregnancy I've had super bad constipation. It was the only pregnancy symptom I had until I took a test when AF was late.
I'm a FTM and currently 13+3 weeks.
Obviously there's a high percentage of people who poop during child birth but I can't help but feel so scared I'm going to give birth to my baby whilst trying to poop with this horrible constipation. 
I've tried everything and so far only massaging the lower part of my back when I'm on the loo helps.
Can anyone else suggest anything??