The earliest signs of pregnancy do differ between women. I will say that the signs most report early tend to be tender breasts (the areolas, or circles around your nipples, may darken as well), the need to urinate more often, and nausea. However, most of these signs start showing up right around the time you would be expecting your period, so it's all pretty simultaneous. Some women simply "know" that they have conceived. Others have a feeling of bloating or fullness. Others have slight spotting, which may be a sign of an embryo implanting in the uterus. But some women don't have these symptoms and are surprised when they miss a period and find out they're pregnant. It's very individual.
The Mayo Clinic has a pretty thorough page about early symptoms of pregnancy:
Bbboo2u, I would like to encourage you to tell your boyfriend. Since the two of you are obviously very close, it seems like you should share this possibility. You are concerned; he should share that concern. You have to worry before you know anything; it seems only fair that, since he shares the responsibility for making birth control decisions, that he also should be aware of such things. He should wait with you for your period, and, like you, have that time to think about the "what ifs." That may make him more careful in the future if something similar is about to happen.
Good luck to you, I hope that your period comes right on time and doesn't stress you out too much. Please do write back and let us know what happens, OK?