Was the last egg laid on Mar. 1? If not, or not sure, I'd be inclined to give it another week.
My goose laid her eggs over a 2 week period, then 3 more while sitting on the nest. I didn't mark any, but just knew from my daily count (she lets me go under and see what's up)
So, when I thought the hatch would be around the beginning of the month, I let it go a bit longer and she managed to get all the eggs to hatch within 24 hours of each other, but ~2 weeks later than I would have expected them.
My point is, are you sure it's time to toss them?
When you can get under her, you can sometimes tell the yucky ones - they will be lighter than developed eggs.
As for getting under her, that's a tricky one. I had to be very stealth at first, watching when she went off the nest for water and a snack. It was usually late in the day after I did my chores (of course) so I started making another pass, leaving some tasty greens and scratch out away from the nest. Once I caught her off the nest I'd make a run for the goose house, nip in and close the door to keep the adults out, then do a quick egg count, check the nest, etc. I kept it short and sweet so she wasn't TOO upset.
Good luck!