This is Not the Jewish Calendar
If you're interested to know why, just research the Hillel II calendar. You'll find that the rabbis in the fourth century A.D. invented a new way of reckoning the days.
** Pesach is technically a meal, not a day. The Pesach meal begins at dusk on the 14th day of the first month. The lambs are slaughtered earlier that day and prepared during the afternoon. Thus Y'shua was crucified on this day. It is not a Sabbath.
The day of Passover shifts from year to year on the Gregorian calendar, but First Fruits is always on Sunday. In 2018, the timing of Passover and the start of Unleavened Bread just so happens to be on the first day of a week, therefore the end of Unleavened Bread a week later will intersect with First Fruits.
What If the Real Dates Occur a Month Later?
Elohiym understands the challenges that present us in this ungodly world. Our good heavenly Father only expects us to do the best we can. As long as we have genuinely tried to observe his instructions, we've done our part.
Of course, if you can adjust your schedule and take off the appropriate days once we know for certain that the new year has begun, by all means do so. But if that's impossible for you, no biggie.