Yes, I experienced constipation with hypo, too. As GravesLady said, I took an ayurvedic remedy called "traphala," (found at the health food store), and I was back to normal with a week or two. Important to drink LOTS of water and keep up with the fiber. I also take Prilosec for GERD which can be constipating.
Even though your TSH has come down, it will take a while for your body to resolve symptoms.
Good luck!
I took a laxative aid for a month or two, then everything went back to normal. No problem since and that was 11 years ago.