I can understand that you are scared. But let's take this one step at a time.
First of all, you don't need to go to a hospital for this if there are walk-in clinics or urgent care centers. They are less expensive and you don't have to wait for all the emergency patients to be seen. Of course, your college health center or a clinic (be sure it's reliable, like Planned Parenthood and not a fake knock-off with a political agenda). If you call a PP clinic even if it's too far from you, they can perhaps refer you to something local. Remember that these clinics do blood work, pelvic exams, and much more, with reassuring and knowledgeable counselors to talk to.
Second, your symptoms could be related to pregnancy, but they could be related to something else, and often something minor. For example, you can have an anovulatory cycle, where no egg is produced, and therefore there is no egg follicle to secrete the hormones that signal the uterus to shed its lining. Happens all the time, it's normal, it's fine. Having some minor bleeding (your brown flow) can happen. As hormones build up, you can get breast tenderness and so on. It usually fixes itself in a month, which could mean you're going to get a period. However, your dates may be off - so a new period won't necessarily come a month after the last one that should've come but didn't.
But yes, this can also be related to pregnancy, and it can also be related to other hormonal imbalances. It's hardly ever awful and dire, just sometimes something that needs to be dealt with. I don't understand your question's title, that you "can't test." Why not?
Third, you need to educate yourself. Condoms are the only protection against STIs, so it's good that you used one. However, a lot of men don't know how to use them safely (yes, there's a right way and a wrong way), and they are far from foolproof against pregnancy. So you need a reliable method that you can use and that fits with your lifestyle and medical history. A good reproductive health care counselor can help you narrow down some options and learn proper usage, and you can finalize your decision with a doctor. It wouldn't hurt for your boyfriend to attend some of the session even if you have and want private time - he needs to be educated and can do that on his own too.
For now, you're in limbo. You need to take steps as if you are pregnant, and as if you are not. So you cannot start something like the pill or implant unless you get a normal period. But you also should be making decisions on what goes into your body (smoking, drinking) as if you are pregnant, if you would possibly continue the pregnancy. I think you need to stop having sex until you resolve the medical situation. I don't think you have to swear off sex entirely until you are ready to be a parent, but you absolutely have to do some thinking about what you would do if you are pregnant now or if you become pregnant unexpectedly later on. This is what mature women do - they figure out their values, they learn to assume that men won't always stand by them, they know that even in a great relationship the issue of pregnancy is the woman's to deal with.