Here are two helpful tips to remember to help you interpret the Torah when it comes to the Calendar and the Holy days.
- Every Holy Meeting is the Shabbat. But every Shabbat is not necessarily a Holy Meeting.
- Even though a week is exactly 7 days, there are 8 days between Shabbat and Shabbat. So in some cases the word "week" should be understood to be referring to the 8 day period and not 7 day period. The only time when the week was 7 days was at the Creation Week, since there was nothing (no Shabbat) before the 1st day.
And here is the bonus tip: expression Holy Meeting (miqra qodesh) = expression Shabbat Shabbaton = expression Shabbat when it comes to Holy Meetings. But always remember tip #1.