Actually, I didn't contrive those definitions, Webster did. Sorry to disappoint you. Nowhere in the (adjective) definition does it state that one *is* homosexual by being attracted to one's own sex, simply that the "attraction" is a homosexual one. One who has both homo and hetero attractions would, by definition, have bisexual attractions. One who acts sexually with members of both their own and opposite sexes would then be leading a bisexual life-style.
However, one may claim (noun) homosexual/bisexual/heterosexual as a label if one cares to solidify their sexual preferences into their personal identity.
I happen to believe we are so much more than simply whatever label someone, even Webster, puts on our sexual actions and attractions. Labels are restricting, confining, and are used quite frequently for lazy prejudging in place of individual thought.