You might try to just change the tickets to next year if you can commit to dates. That could be easier than trying for either a full refund or additional time to use a credit. YMMV.

Since you seem to have passports, Canada could be interesting: Vancouver, Montreal, Quebec City, Toronto, although with their French heritage, Montreal and Quebec City are somewhat foodie places which might not appeal a lot to someone who's pregnant and therefore cannot drink wine and might want to eat familiar things. Just make sure you have medical coverage outside of the USA.

Depending on dates, many places will be crowded in June, with limited hotel choices and high rates. This would include Hawaii and the Minnesota north shore, but I suspect cities like Vancouver, Seattle, and Portland would be more reasonable as well as being unlikely to be very hot.

Does Alaska interest you?