Worried hcg levels aren’t doubling at 6 weeks

I’ve been having some right side cramping so my nurse had me do a blood test at 6 weeks and then again at 6w2d. Well my numbers didn’t double… my first was 32314 and my second was 47670. Should I be concerned? I’m hearing mixed reviews about doubling time. Some say 48 hrs at 6 weeks and some say 96 hours. I had an ultrasound done on 6w1d because I was spotting and baby was measuring a day ahead with 122 heart rate. I had a mmc last year around this time so I’m just crossing my fingers.