HSA Contribution/Medicare

My husband and I both work for the same company, he full-time and me part-time.  I am on his HDHP insurance as a dependent.  We are both over 60 and he contributes the maximum amount to his HSA.  In June of 2019, he went on Medicare while both of us stayed on the HDHP for the entire year.  He contributed $3334 to his HSA ($7000+$1000/12x5) for 2019.  I opened a HSA for 2019 but what is the maximum amount I can contribute?  I come up with $2625 ($3500+$1000/12x7) but the Turbo Tax calculator shows more.  Thank You