Oh, just to give you a clearer idea on how sex usually happens, there are 2 ways:
(1) Committed relationship sex. This is where you find someone you really like on more than just a physical level and you develop an actual attachment/romantic relationship. This goes on for some time and eventually the two of you decide you're going to take things to the next level. Presumably, if you get to this point with someone, they know about your body issues and are willing to do what it takes to make you comfortable, including allowing themselves to be penetrated or having non-penetrative sex where your clothes stay on or just agreeing to call your anatomy by the names you prefer. Whatever ends up happening, it's something that's negotiated between you and your specific partner as part of an ongoing process of discovering each other's likes, dislikes, and quirks. It's not really worth planning this sort of sex until you can plan it with a specific partner.
(2) Casual sex. This is where you hook up with a friend (long-term or short) and have sex that's not planned in advance. In general, you start out doing something not overtly sexual with the person - going out for drinks, watching movies, whatever - often in a group. At some point the two of you find yourselves alone together (or arrange to be alone), and at some time after that you begin to do things that are overtly intimate or sexual. This is where the potential for sex actually begins to appear - and at this point, again, you're with a specific individual, one with individual desires and boundaries just like your own. And you can communicate with them about what you want and where your boundaries are. If you're simply not compatible (or not compatible for anything beyond a certain point) there's no harm, because there's no attachment. But if you find your mutual drive to have sex with each other is stronger than your/their inhibitions, there's no harm in that either.
You don't have to decide that you're going to have sex with someone until (a) you're in a position to actually have sex with them and (b) you've communicated what you want and gotten a response from them individually and (c) you know what your physical/emotional reaction was to that reaction. Nor do you have to rule them out before you get to that point just on the basis of what you think they'll want. The world doesn't end if you make out with some guy and then find out he's also a top and neither of you wants to switch. With any luck, you had fun getting to that point.