In my opinion, you are straight but are getting excited by just visualizing and imagining yourself in the positions that the guy is in. There are many men, for instance, that would rather a woman give them a handjob than engage in intercourse for a variety of reasons, at least some of the time.
In your case you will have to find out yourself by asking relevant questions from time to time. Analysing your feelings in regard to sexual leanings.
Is a label really necessary? Your sexuality is all yours and no one else's and it does not need to be similar to anyone's. You don't have to tell your mom anything about what you enjoy seeing when you watch sexually explicit material or if you see a guy and think he is cute. Most of all, you have to be honest with yourself. I am bi (really pan but try explaining that to people who believe in pigeonholes regardless of who they are!) and it took a long time for me to admit it to myself. My current girlfriend knows but the one I had in high school doesn't need to know (more)
To continue, first be true to yourself and enjoy what you like and like what you enjoy without a label --if, later on, you feel you need or want a label, accepting yourself first as you are rather than trying to fit ANY societal mold will make it both easier and clearer. Second, intimate relationships need intimacy (hence the name) to succeed so you may need to be honest with her (don't worry so much, if she is younger than 35, she might just shrug her shoulders and ask you if you are exclusive (likely her only real concern) and if you are, she might ask you some more questions or maybe ask you some questions later but curiosity, not fear, will drive those questions. In case it comes up, almost all crossdressers are straight and gay men tend to be far more masculine behaving than either people expect or would believe. Once, "real men" smoked and joined "women haters clubs" --yes, that was a real thing-- and she might say something hurtful that she might come to regret later; just tell her that a real man is a man with the courage to be true to himself and to love without fear.
I once knew a woman who could only engage in sexual behavior if it involved tickling. It wasn't some sort of association with childhood or something, it was the loss of control that made it sexual. It sounds like you enjoy seeing guys (you may or may not like it yourself) in situations were control is lost or power is exchanged. Bondage is often part of the "ritual" because it may ease the societal expectation that "manhood" means control in the bedroom --doing to rather than having something done to. Penises are fun to play with and they are different than vaginas --penises can bounce, twitch, grow dramatically from flaccid to erect, darken with arousal, most of all, they can be handled rougher and more actively than a clit and still result in pleasure for the owner. Nevertheless, touching one, or sucking on one or penetrating or being penetrated does not make you something or take something from you --any more than vaginal penetration made you male. Gay or something means that you can form emotional bonds and/or prefer to form emotional bonds with the same gender (want to really think about it, imagine someone who is with a transman; is he gay? straight? does it matter?) whereas a bi person can be heteroromantic or biromantic or homoromantic --who do you love vs who do you enjoy playing with. Someone may believe that you are this or that because that is their opinion but who cares what they think and why do they either need to know or need to give their opinion anyway?
Your mom might surprise you, many people have fears that have more to do with ignorance from lack of contact or knowledge than any actual dislike. Your girlfriend might surprise you, she might want to watch the porn you enjoy with you (since you are exclusive) and/or she might let you in on a deeper part of her sexuality or yes, she might freak out; however, twisting yourself in knots because of what she might door think only guarantees your future unhappiness.
Incidentally, outside of religious organizations, which still maintain horridly backwards and deterministic believes concerning sexuality, the American Psychological Association and the American Psychiatric Association removed gender issues from possible diagnosis long ago. Someone who is distraught because their religious mania conflicts with their desires may need help making sense of and resolving the conflict but there is nothing wrong with them. Fetishes that do not involve paraphilias (they are not exactly the same thing) do not have any diagnosis associated with them. So, any counselor that says things like that is worthy of seeing you walk away. You can find better through the APA website.
You might not enjoy either tickling her or being tickled by her. You might enjoy or not enjoy being tied up. Who says that what you like to watch has to match what you like to do? Imagine if she took a webcam and pointed it at you while you had your hands tied to the headboard. You are on your knees and have a monitor in front of you and she does something to you... say, she starts masturbating you (lots of lube) and you watch it on the monitor... some people need blindfolds or gags, you may just need a tough enough monitor so that it can fall from the bed and still work :-)