5weeks & 5days pregnant with light bleeding

So my hcg numbers went from 623 on Monday to 1863 on Thursday. However I’ve been having light spotting to light bleeding since Monday. From brown to dark red then back to brown. Nothing to feel up a pad. Only when I pee and wipe I see it. I fear I have a small blood sac and my midwife said all labs are normal. I’ll be getting a ultrasound sound in 2 weeks to see if everything is ok. Has anybody else experience this? I had a miscarriage July 2017 and I just want to put my mind at ease.Help!