Trying To Concieve. Taking Dong Quai Capsule. Experiencing Brown Spotting. Due To Pregnancy Or Miscarriage?

Hi, I have been trying to conceive for six months now. I am a 28 year old healthy mother of 2, but i got impatient not getting pregnant as soon as i would like and I was having really bad pms, maybe due to the stress of not getting pregnant so, I started taking a chasteberry and dong quai combo capsule once a day, which are 350mg of chasteberry and 150 mg of dong quai. i took it every morning this month up until a week before my period because i started have pregnancy symptoms and i knew i had read somewhere you shouldn't take while pregnant. Well, I got my period, but it was NOT normal. I usually bleed for 5 to six days with medium to heavy flow the whole time, but this month it was super light almost like i was bleeding from a wound and it was trying to stop and clot....just on again off again spotting for two and a half days then the blood turned to brown/black thick (yuck) spotting, which I have never had. I took a pregnancy test at 11 days past ovulation, 13 days past ovulation and then again yesterday when the brown spotting had completely stopped. They were all negative. My breast always stop hurting the day before i get my period, well this month they started hurting more the day I started started spotting and today even more so. I guess my question is can i still be pregnant, was i ever, or did i miscarry because i found online women take dong quai on purpose to miscarry...which i didn't know and i just feel awful now.