Still pregnant?

I'm not really sure where to start, so I'll just get straight to the point and hope someone can tell me more..?

My period was supposed to start last Monday, but it didn't. At the time, I wasn't thinking about a possible pregnancy because I had stopped a 2-week course of antibiotics about a week before my period was due. I thought it might just be delayed because of the meds. On Tuesday morning, still no drop of blood, so hope started to rise. All afternoon I noticed some brown discharge when wiping, but my period didn't really start. In the evening, it finally did, and I thought, well, let's hope for the next cycle... On Wednesday (yesterday) I lost dark red blood, but less than usual. Last night I lost almost no blood, and today (Thursday) I've only had a few drops on a panty liner for the whole day. I still really hope I'm pregnant because I read on several forums that some women had a period for 2 days and turned out to be pregnant. Has anyone here experienced this too? And is there someone who can help me out further? I don't have a fever or sore breasts. I do have a lot of nausea, and I feel quite short of breath at times, then suddenly super cold. I also have some diarrhea (sorry for the details).

Best, Xx