i didnt use ivf but yes i had low hcg at first bt. 12dpo it was 19. was told it was probably not a viable pregnancy and given the amount of pain i was in they thought it was ectopic. however all was well. the second bt came back low too at 341 a couple of weeks later but the third came back super high over 7000 about a week after the second bt. so yes been in the same situation. its early days yet so try not to stress too much it could just be that its so early