Health coverage after losing my job: marketplace or Medicaid? (Boston)

My employer coverage ended at the end of the month and I am trying to work out what to do as a bank teller. I have read a lot of threads here and could not find my exact situation. I do not want a gap in coverage. Is there help filling out the forms?

Thanks for writing this out. I went through something close to it 5 months ago, and it got easier once I kept a simple log of every call and form.