Stressing out - experienced mom's, can you help?

So at my ultrasound yesterday, they saw two gestational sacs and confirmed that I am having twins. One measuring at 5 weeks and the other 5 weeks, 3 days. No fetal pole yet, follow up ultrasound on Friday and I see my OB on Monday. The problem is, I went to the hospital for period like bleeding, the only pain I have is on my left ovary but I have a 2.5 cm cyst and I have endometriosis. The doctors are not concerned by this bleeding at all because of the US and my hcg levels are still going up. They didn't find any reasons for the bleeding but did say it could be from my endometriosis. Has anyone had bleeding this early and still had a healthy pregnancy/baby? I need some reassurance, I am so scared.