Hcg levels slow rising


Friday the 26th I went to the hospital due to dull pinkish discharge that stop after I wiped.. they checked my blood to confirm pregnancy & I saw my HCG levels were at 120, the doctor said my levels were to low to do an ultrasound so come back 2 days to see if they doubled, I came back in 4 days & my levels were only at a 145.. anyone else had this issue and had a successful pregnancy?? (I am 5 weeks 1 day today)