Hcg levels

Monday evening I went into hospital and they took bloods at around 7-8pm for hcg levels they come back at 2000 then I went back in this morning for a early scan and they could not see anything therefore they think I could be earlier than 5 weeks they gave me some medication but also took more bloods 11am to check my levels and they have come back 3541 they said they haven’t gone up quite like they want them to so I have to go back in Friday for more bloods they said it could be a failing pregnancy, ectopic pregnancy or what, has anyone else had the same or similar? TIA