How To Avoid Bleeding During Pregnancy?

Well I had started bleeding friday morning like a period and haven't seen blood every since then. I went to the er and they stated that they think I was having a miscarriage but when I had a vaginal ultrasound I just seen the sack. The ultrasound tech said it was possibly to early to see a baby. I believe I still am pregnant because I haven't been bleeding since then. Please give me your opinion.