I'm scared to stop taking fertility blend now that I am pregnant?

I am 39, almost 40. I have a history of miscarriage, but it has never been proven to be a progesterone problem. I do have children and had no problems with those pregnancies. I myself has suspected for years that my progesterone is on the weak side. I used progesterone cream with 2 of my full term pregnancies. I had a miscarriage about 9 months ago, and it completely messed my cycle up. I bled non stop, and my charts showed I wasn't ovulating, as my temps were low for months. My charts during regular months have sometimes shown my progesterone to be struggling after ovulation. I started taking fertility blend out of desperation to control my crazy cycle. It worked beautifully. When we were ready to try and get pregnant, I continued on the fertility blend. I just found out I am pregnant yesterday. I am now scared to stop taking the fertility blend, because I am afraid it will cause a drop in my hormones, especially Progesterone. Should I wean myself off of it since I have been on it for 6 months? Should I immediately stop, and use a progesterone supplement to support the pregnancy? Just fearful that I could cause a loss of the pregnancy because of this! Just so unsure what is OK? So many contradictions about the use of fertility blend/vitex? Thank you so much for any help!