Hcg injection as luteal phase support

I had a FET done on 4th November and my beta test date is 18th November.

They said the embryo quality was just average and not good.

They did a Day 3 , 8 cell embryo transfer.

Last month i had fresh transfer and it failed.

They gave me 5000iu hcg on 4th, 7th, 11th and 13th November.

I am afraid that the beta test on 18th will show the effect of left over injections.

How many days does hcg take to leave our body and what value should I expect on 18th to believe in my pregnancy.

I am so frustrated.please help.

Ttc#1 since 7+ years with pcos.

I am 35yrs old