I lost and my rating went up?

I started playing correspondence chess on the ICCF server’s last summer and as you can see from this my rating, I am not that good. This is especially embarrassing given the fact we are allowed to use chess engines for help. But that’s not important right now. I received my first official rating coming into 2015 and held a 1682. Somewhat respectable, but not chessmaster material. Then this happened.

Oh, this is just embarassing
Oh, this is just embarassing

My first game in the new rating period finished on December 10th with a loss. So I asked the server to forecast my new rating and my rating went up! The forecast rating was 1688. I lost and picked up six rating points. So how does that happen?

The Elo rating system used by the ICCF counts the total difficulty of all the opponents. Alexandre Duchardt, who beat me, was rated much higher than I was. He was also rated much higher than my average opponent. So the net average difficulty went up and those prior few wins were worth just a bit more and the rating goes up.

For reference, if I predict today, I score 1722.