Short answer:
No it's not irrational if you feel this way, and this is an answer coming from a person who is disabled too.
Long Answer:
So as already said, I'm disabled myself. Seeing that this is a public forum which treats a lot of sensitive topics I'm not going to say too much about myself other than that my disability is definately visible, and can cause me a lot of chronic pain from time to time. Personally I think that your feelings are more than valid due to the fact that nobody will ever truly know what its like to walk in your shoes except (as already mentioned by some commentators before me) you yourself. The problem that I personally see with the comments from the people around you is that these comments don't reflect the statistical reality of things, meaning that its extremely hard to achieve big things in life, and having a disability most definately doesn't make things any easier. And while yes, there may be people who are worse of than you, you should always keep in mind that if you look around hard and long enough, you will always find someone who is worse of than you. And while yes, there are people who are extremely successful with their disability, bear in mind that the success stories are still extremely minute compared to the stories of people who weren't so lucky (you know, those stories you never hear about because they wouldn't keep you going or wouldn't keep you motivated in any way).
Last thing that i wanted to talk about here is that as with all things in life, there's much more factors that will influence how you feel in life (besides the disablity). Factors that range from the country you were born in up to the amount of help you can get in the place where you are at the moment.
Sorry for the long rambling text, i hope it's at least partially understandable. I'm just really interested in this topic, seeing that im personally affected.