How do i no if dyslexic or is english not first langauge?

I was on de forum that me n my friends write on sometimes and someone told me that english aint my first language cos i cant spell or punkuate propally but de mum n de teachers always said tat i am dyslexiac and tats why im not very good at writing and spelling. What does english not being first language mean? Is it common? Hw can i tell if English isn't my frst language. Woud i be able to speak spanish better if not english? Reeli wanna know if i am still dyslexiac!!!!