Actually, fetishes and main sexual preference do not always line up.
It's due to a quirk in how our psychologies work, and organize preferences into hierarchies.
From what you said you get off on the idea of beign tickled by either females or males (your bi comment) which its really a way of saying that you get off on being tickled period. To your psychology being the victim of a tickling is more important then the person dealing the tickling to you. Thus it's a genderless desire. You'll rise to the occasion (pardon the pun) regardless of who your Ler is.
This gives the impression that you are open to both genders sexually, but in reality it highlights how gender is unimportant to you when it comes to tickling. It's the tickling you are beign aroused by not the tickler. So the 'sexual' aspect of the act is just that, tickling, without a gender aspect. If a machine was doing it you'd be just as aroused, but it wouldn't mean that you were sexually attracted to machines.
So you are heterosexual when it comes to regular sexual preference.
and
Your are by appearances bisexual when it comes to being tickled. But that does not needfully mean you are bisexual, just indifferent as to who (or what) tickles you. Which in turn leads to a sexual response.
Now if ONLY the idea of men tickling you gets you going, then you have a clear split in your regular/fetish gender preferences, and that would speak to a bisexual aspect in play. Because the fetish only 'works' if a specific gender is attached, and that becomes a factor in greater gender preference in a sexual act.
In short, we are complicated creatures, and the binary Hetro-Homo box set with Bi being subtitled to both at once is inadequate to really describe how our sexualities work. It's rarely an All or northing thing in our preferences, more of a continuum.
In the end if you find things you like, and it doesn't trouble you, and everyone is on board with how they stand in relation to each other, then its all good.
Myriads