Dear Deborah Lynn,
MAZEL TOV for such an incredible time. Please consider 3 items; especially the 3rd!!!!
1. There might be a big difference in the rabbinic/Hebrew calendar that is set years in advance and the Biblical calendar (set by G-d). This year the barley was very well verified as Aviv prior to the pre-set calendar, so they were different (a month off). A second consideration is that there is at least one instance that for practical reasons Passover was not celebrated on the Biblical calendar and G-d still accepted it being celebrated later.
2. Numbers 9:6-11 reads:
"But some of them could not celebrate the Passover on that day because they were ceremonially unclean on account of a dead body. So they came to Moses and Aaron that same day and said to Moses, 'We have become unclean because of a dead body, but why should we be kept from presenting the Lord's offering with the other Israelites at the appointed time?' Moses answered them, 'Wait until I find out what the Lord commands concerning you.' Then the Lord said to Moses, 'Tell the Israelites: When any of you or your descendants are unlcean because of a dead body or are away on a journey, they may still celebrate the Lord's Passover. They are to celebrate it on the fourteenth day of the second month at twilight.'"
Dear Deborah, I appreciate your commitment to following our Heavenly Father's will. He is full of understanding and mercy. He knows your heart is not to displease Him, if it is not. You might be more concerned of what family/friends think, but I hope not. Show them the Bible verse above if they question you. I found your article because I was also surprised that it fell in Passover week. The date is not anti-Semitic as at least one is saying. It's always on the pre-set Patriot's Day, as you probably know. Be encouraged in truth and mercy. We won't know for sure on the calendar until the next agricultural cycle.
3. Unless I'm mistaken, in 2017, on the pre-set rabbinic/Hebrew calendar, the 7th day of the Omer falls on the day after the marathon (sundown of that day). That is the Sabbath of no work. Are you aware of any prohibition from working on the 6th day of the Omer? If not, a Sabbath of no work would be a wonderful time to celebrate after you finish the marathon. Shalom.