a week late on period and spotting a light pinkish brown/pale red

I am afraid I might have a chemical pregnancy(or very early miscarriage...). But idk for sure....I was supposed to start my period a week ago exactly, and I am usually..no, always, right on time-- like the 28th day mark. A day after my period was due I had spotted a little bit of light pink. I wiped a couple times and then it stopped. then 2 days after That, i started bleeding but i knew this wasnt my period because it was thin light and stopped a couple hours later. this all started up AGAIN, the Next day(Yesterday)--- only the difference was that the spotting was a pale red/ brown or blackish kind of color, and again stopped after a few wipes... Today is the same thing but more red and brown rather than pink...Soo Yeah,... This has been going on for 4 days now.. and I am worried.. Ive already had a miscarriage before(last fall) and am 19 years old... my boyfriend of almost 6 1/2 months won't believe it might be pregnancy, because we always used a condom(but there could've always been the slight chance of "Precum" or a tiny hole in the condom or something...) I just know that this isn't my period though,- I mean, i am cramping occasionally but not anything like my period cramping yknow? and like, most of the cramping during these past 7-8 days has been in my lower abdominal/ pelvic regions. My boobs are Killing me- I'm a small average sized girl- n they are becoming noticeably bigger and swollen... Been extremely emotional, moody and tired lately... My libido is down--> I haven't felt up to having any sex since all this has started...like i cant get into it or something. I have also been real nauseous on and off throughout the day during this past week; along with frequent urinating, headaches, and body aches and pains ... I'm going to wait a little bit before I take another test(last was negative).... I admit I am scared to take another one, only because of what it can or cant tell me..    Sorry I dont ever ramble like this, but I am seriously worried and freaking out..Just a WorryWart trying to find out if Im pregant or if something is really wrong ....And I dont think i can take another miscarriage... :'( Can anybody please give me advice on this????? thanx...