Annoyed and scared

I am approaching 40 years of age and have 3 older kids. For the past 10 years I’ve wanted another child or two but my tubes were tied. Within the past two years I have gotten my tubes untied and 1month later was pregnant but miscarried😢 I have not been able to get pregnant again yet so every month has been frustrating when AF comes. My OBGYN says to purchase geritol liquid for me and the husband to take so we will start taking them tomorrow. 🤞 i am really scared about having another child at this age but I feel so young and active so we shall see.