Went to the ER for cramps...

I went to the ER yesterday for cramps and they did an ultrasound and found out that I was 4 weeks and 6 days with a gestational Sac implanted to the upper left side of the inside of my uterus. They said it's not in my tubes and is in the uterus but it's too close to the left and should be in the middle of my uterus. Could this be a viable pregnancy? Or ectopic? They did not see a fetal pole yet because they said it could either be too early or a possible miscarriage may happen? Confused could this be a viable pregnancy if it is too early?