HCG LEVELS IN EARLY PREGNANCY

[Beckys1990]

Hiya everyone
I'm very early on in my pregnancy I have in the past gone through the multiple miscarriages then I had my daughter who's now 3 i found out I'm now pregnant and panicked abit worrying about everything I went through previously I have been having my hcg levels checked every 48 hours
I can't remember exact numbers but
1st test -149
2nd test 48hours later- 330ish
3rd test 48hours later- 770
I was then sent for a scan which was 72 hours after the 3rd test they couldn't see anything on the scan to confirm everything was as it should be there was a 5mm fluid filled sac they then retested my HCG levels
4th test 72+hours later- 1450ish
I'm now worried that this rise isn't normal as its only just doubled within the 72 hours I'm not being tested again they're waiting and scanning me next week (wed) anyone else seen this before and been fine am I just being silly worrying like this I'm just keeping everything crossed that there's something more there next week
Thanks
X