So what kind of insight do you want?

Does getting sucked off by another guy make you gay (or bisexual)? No, of course not. Let's face it, men have their needs and one of those needs is to get a nut off with some regularity. At your age of 18 you're probably horny 24/7 and need to get off at least daily and preferably multiple times a day. If you don't have a pussy to fuck and you're tired of jacking off, find a nice cocksucker to take care of you. A lot of straight guys do.

Does this obligate you to return the favor and suck him off? No, it does not. Cocksuckers suck guys off because they enjoy doing it. If you want to recriprocate, that's fine, and if you do not, that's fine too. So do not feel awkward if you do not.

Thousands of men have claimed that men give better blow jobs than women. I'm not saying this is true, but it stands to reason. A male cocksucker has a dick himself and the bottom line is that he knows what feels good.

So put yourself out there and let a man suck you off. It's truely a win/win situation. You get the pleasure of getting a blow job and the cocksucker gets the pleasure of giving it to you.
--------------------------------------- added after 7 hours

some further thoughts on this matter.

Perhaps I should have asked this first, but where is your head on the subject of man-on-man sex? Could you accept a blow job and then say "Thanks, man, I really needed that" and not give it another thought? Or would you let being horny drive you to doing it and then be overwhelmed with guilt and remorse later? If the latter, DON'T DO IT. A lot of straight guys are totally cool with fooling around with other guys. If that's you, go for it.

And I might add that a lot of straight guys are cool with fooling around with other guys and not just in inserter roles. I've been with straight guys who sucked cock like champs or took it in the ass with the best of them.