I don't think you are being unreasonable. BUT it is possible that they were also being reasonable within their own constraints too. They may have their own reasons why they cannt / won't change things to fit around you. It may just be that this was a time where things couldn't quite work out so everyone's needs were met.
It is sad when that happens, and usually both sides end up feeling jibbed and misunderstood by the other. But it happens all the time.

We have this issue with DH's family often. We travel a LONG distance to see them, but our personal constraints / desires for the trip often mean a conflict with regards to who we see, for how long, and where. They want things their way (for whatever reasons - valid and not so valid) and we are unwilling to change our entire trip just to suit individuals (be it his mum or his siblings) because it means it does put us out significantly. I can see why 'they' prefer the options that fit around them and are easier for them, but they arent readier for us - and part of me cannt help but think 'hey, we came ALL this way, surely you are willing to come just that little bit, which is nothing in comparision". ((or at least not get stroppy just because we don't do what 'you' want))

So, no I don't think you are being unreasonable given your circumstances, BUT you don't really know what their circumstances are either and it is unreasonable to think that they should have to change whatever plans they have in place to suit your situation.