Short answer
Your next order date is based on your dose and how much medication was sent. If it looks far away, your current supply still covers you.
How long a shipment lasts depends on your dose and how much medication was sent. Your dose sets how much you use each week, and the amount sent sets how many weeks that covers. So two members who started on the same day can have different refill dates.
Your next order date is based on that, not on a fixed calendar. If your next order looks further away than you expected, it's because your current supply still covers you.
Where to find your dates
Your My Orders page shows your next anticipated order under Upcoming Anticipated Orders, along with tracking for orders that have shipped.
See Do my refills ship automatically? and When will my order arrive?