I FOUND IT!

I finnaly know now what the problem was, for some reason the developer of the Shifter app decided that it would be a good idea to use integers for the months. So jan is 00, feb 01, etc. This took me way too long to figure out, but I eventually did. I found out because I saw my little brothers birthday in the notes, but it was shifted by exactly one month and then I looked at all the dates and saw that years ended with 11, instead of 12. Now I just need to fix a little problem I created myself by using timezones to parse the dates. This causes dates to shift an hour because of winter time.