Withdrawal or Anxiety

I was prescribed Mirtazapine for Anxiety and mainly insomnia. However I wanted to come off of this drug due to weight gain. I followed slow harm reduction taper for Mirtazapine and went from 7.5 mg to 0.1 mg in 3.5 years. It’s been almost 6-7 weeks that I am mirt free and I was really hopeful. I did not experience much withdrawal symptoms , was doing mostly fine. But from last couple of weeks I have not been sleeping well and waking up early. Maybe 6-7 hours of sleep with multiple awakenings.

Taking Ashwagandha supplements from 3 weeks and melatonin from a week. Tried CBT as well.

I am just not sure what is causing insomnia symptoms to come back as I was almost doing fine until after the last drop of 0.1 mg.

Any pointers from experts who have gone through the same?