Is my wife Lesbian

Hello

I am 33 yr old and married 2 yr back,my wife is 31 yr old.She work in a PSU bank,since 1st day of our marriage,she was not interested in sex at all.Initially she said that we will do in new house,later always make excuses of work,closing and other.If some time I try to do she got angry.Since childhood to MBA ,she had studied in girls only school/college.I had doubt that she is lesbian or bi sexual with more attraction towards girls.

I don't have any problem with that but atleast I should no,how can I confirm that?Any suggestions.