Can some one help me with hcg levels?

Hi i just found out am pregnant but am to scared to even get excited or happy because am scared i have another miscarriage that's all that's on my mind! I have to go back to hospital on wed to get the levels checked to see if they have doubled the reason i have to go is because i have been going thro fertility treatment. But yesterday my level was only 75 the clinic said that was normally tho as am only 4Weeks and said i would also be booked in for a 7wk scan. But i got a scan yesterday to check the lining of my womb and that was 12.5 dont know if that's good or wot. But i also neva noticed anything else on my womb tho. Can anyone tell me if the levels sound right? Am just so scared something is going to go wrong. Thank for any help x