spotting issue

I am currently experiencing a slight spotting today. Brownish ang kulay. May last period was on January 28. May supposed to be next due was on feb 24. I tested for pregnancy test last feb 28. And it was positive. I went for an appointment sa OB kahapon march 6. Sabi s ultrasound wala pa daw implantation. So i need to back after a week. Ngayon ang taning ko, ito po bng naraaranasan ko eh ang tinatawag na implantation bleeding? Nagwworry din kasi ako kasi first baby po.