I wouldn't be overly worried.  It's probably mostly inflammation and gas.  Your symptoms will probably fluctuate quite a bit for the first few months while everything settles down, then continue to improve for 12 months 2 years.

For now, just accept you will be making lots of visits to the bathroom, try not to strain.  What really helped me was lying on my front, this helped gas escape and also reduced my bathroom visits (I still do this now 3 years on)

As Bobish suggests, straining is a *bad* idea. It can usually be replaced with patience - a second bathroom trip a few minutes later, or waiting on the toilet for a while. Another thing that might help is a bidet. Some of the symptoms you are experiencing may be related to straining rather than retained stool.

Your body is getting used to a different method of pooping, and your sphincter has a slightly different job than it used to. You’ll get there.

I got a bidet and sudocrem. But the bidet only seems to get out some of it at times. It seems to be better today, but mainly because I had a half hour long bath before bed last night. 

If a long bath makes you feel good then that sounds like a great plan, well worth repeating. Time is likely to be your greatest ally, but whatever you did most recently might get the credit.

Thanks Scott, today was a lot better. No burning or straining. Only issue I'm having now is still getting use to my pouch filling. Gives me some awkward cramps that last a few minutes. But they are nowhere near as bad as it was the first few days. So I'm assuming with time the cramps should mostly go away. 

It should get better, you and your body will figure it out. I will suggest that planning to have a longer sit during your bm may help, just giving it time rather than straining. I know someone has posted on here concerns before about how long it takes sometimes. Hopefully you aren't already sitting for to long but I often take 20min, or longer especially before bed.

Good luck