Never Expected Problems

Hi everyone
After ttc over 1,5 years, 3 IVFs and 1 Frozen Embryo Transfer my pregnancy test is positive. I always thought the day i get the positive all my tears and fears will dissapear. But no i am so stressed. 
I already got pregnant with the 2nd IVF but my HCG didnt rise correctly and a misscarried. 
Now a positive again. First Beta at 9 days past transfer which is 14 DPO was 86. 
Second Beta Test at 16 DPO was 218. i know it Doubled. But i feel its still on the low side. 
So today at 20 DPO i did another test myself to reassure myself. The line is strong but just like the 15 and 18 DPO one. No difference. I Expexted the test line to be as strong as the Control line by now. 
Dies anyone experienced anything like that and what were your betas?
I am so terrified that this will be like last time. 
First Photo is 18 DPO Second one 20DPO.