Hi Vivek, I just made it back into Thailand myself last week on a Non-B Visa. Regarding insurance, I had to buy it twice because the one I purchased from the USA didn’t work.
I wrote a whole blog about my experience getting back (below) this week.
I can help you with the insurance - our team now issues it in one/two days and it comes with the certification letter to authorities. Just message me if you need help -