Beta 4

4 6 weeks today 19dp3dt. Beta went from 510 on Monday to 1367 today. Seen in the ER this am for periodlike bleeding when wiping. Cervix closed. Ultrasound performed gestational sac not visualized yet. Docs reassured by betas, in fact they drew two while I was there since they initially misplaced my first it went from 1346 to 1367 in less than an hour. Can't really pinpoint bleeding; they seem cautiously optimistic. I go back Friday for a repeat beta and ultrasound. Concerned 1 could this be an ectopic? 2 why am I bleeding like a period? 3 I know it's early, but wish they could have seen a sac. Hate being in limbo. Any thoughts?