Speaking as someone who is dyslexic (I was diagnosed when I was in primary school). The first thing you will realise about a true dyslexic person is that they do not advertise the fact that they are dyslexic, they often as not hide or have worked around their issue(s). Often as not those (not saying everyone) shouting about having dyslexia or similar don't have it and are just too lazy to learn or simply can't/won't do the problem area.
Now on a personal level if I tell someone I'm dyslexic people are shocked, they don't believe me and the main reason for it is I don't advertise the fact that I am, I never used the 'extra' time or help that was available to me while at uni or school. My view was (and still is) simple, I wouldn't get this help in the real world so why have it now, this often made me think about my maths in a different ways, I often couldn't get my head around the topic if the teacher was teaching me, but give me a book and somewhere to write and I can normally work out the technique and that worked for me (and was acceptable for tests).
I got an A at gcse and was basically self taught from a book in the end.
When I did my A-levels I screwed up and got crap grades, looking back on it I now feel it was due to the fact everything was via teachers who to be perfectly blunt were useless at explaining things in relation to the exams we would take. I knew the info (my degree proved that) but due to the methods used to teach I didn't get it right in the exams, and trust me I worked my ass off to try and get to grips with it.
Now to the op, if you feel that you have dyslexia (or any of the other variations) go see the doctor, they shouldn't laugh at you or anything, they should be able to give you an idea if you have an issue and if necessary refer you to a specialist, often as not anyone over about the age of 30 (and sometimes younger) got missed due to the lack of info about it. I'm now 28 and I was lucky I got caught, back when I was younger it wasn't recognised like it is today, there were no certificates either like there are now.
PS sorry for long post.