I'm not a FIRECALC expert either but I agree with hermit on RMD. Like hermit said, you should not enter RMD as separate income, it's from your portfolio. As long as your spending is more than the RMD $ amounts, it's accounted for correctly. And accounting for taxes in your spending is important as hermit noted.
However, I think you may still be able to model your situation in FIRECALC.
On the first page you'd enter spending of $85,000*, a portfolio of $1,840,000 and 33 years if you want to plan to age 95 for example.
On Other Income/Spending you'd enter your SS and the year you plan to start (2018-2022?). And your spouses current year SS income starting 2014.
On the Not Retired page, if you plan to work PT for 3 years, enter 2018 (3+ 1 yr FT) and enter $70,000 (PT income) you'll add until full retirement. I realize that may understate the 1 yr of FT work, but you could add the difference
as a lump sum on the Portfolio Change page if you like, if it's substantial.
*And if you donate to FIRECALC, you can vary your annual spending throughout retirement to account for your future spending reduction from $85K to $70K.
I tried all these inputs one at a time and it appears FIRECALC accounts for them all. And there are probably other inputs you can tailor to better model your situation, but that's what I'd suggest based on what you've shared. Best of luck...