Spotting to Bleeding

Last friday afternoon, i experienced spotting red/brown. So, my husband and I went to OB the next day, the OB said I am experiencing not only spotting but bleeding. So, she performed transviginal ultrasound, in the result, it is the gestational sac appears with no embryo yet. in the ultrasound, I am 4 weeks and 6 days. So, the OB advised me to take duphaston and folic acid and bed rest for a week. and then i will undergo another ultrasound this coming Saturday. As of now, I still bleed but it is just already a little bit. Is it possible that the embryo did not appear yet in the ultrasound because it is too early? Do i have the same case? Thank you.