My HCG ISNT DOUBLING

I took a test on February 15th came out blazing positive.

On February 16th I had mild spotting in the toilet I went to the doctors and it was 424 or 464

Fast forward to today I was 536 which means I’m in the “normal range” but it didn’t double in exactly 48 minutes.

I’m spotting enough to only wear a panty liner and wear it for hours

Has this happened to anyone ? Please comment I truly would like peoples opinions I know I just have to wait but may successful stories? Any miscarriages happen with the situation I’m in??