It isn't that you are being unreasonable it's that you are reacting to a situation
it is normal to feel out of control if something that you want is taken away from you potentially or a spanner is thrown in the works
if you are overwhelmed speak to a counsellor or a sensible friend about it
act therapists are good as they counsel acceptance and moving forward from there
sometimes we don't get what we want but often there is another option we haven't thought about
i say this drawing heavily from experience
get help as soon as you need it though and don't let this become more than it already is