This is exactly what happened to me and exactly how I think! No news is sometimes good news! Good luck!
Same thing happened to me so I had another hcg and have since had my first ultrasound and all is fine, it's normal for symptoms to come and go, mine change on a daily basis now, it's hard to know because everyone is different and being my first pregnancy I had nothing to compare it to. In my head I just think all symptoms can come and go, if I'm not bleeding then it's fine and I'm still pregnant!