My fiancé (F24) and I (M26) got our first positive today in 6 months

Me and my fiancé have been trying for a long time to have a baby & we discovered that she is infertile about a year ago and her doctor basically told us all we could really do was keep trying. We've had this happen before where it'll come up positive but just end up being false, this just hasn't happened in a while. I guess I am also looking for advice here as to what to do if this is the same situation as before? I don't want her to be down on herself again, or feel like this is her fault but I do want to know what to do if it happens again what kind of steps should I take to comfort her etc because I was such an emotional mess the first time I didn't know what to do. We will still see the doctor this week but I'm mostly freaking out because it's a fragile thing for her and I don't want what happened last time to happen again if it turns up false. I feel bad I'm only thinking of the negative side of this when I feel like I should be happy that it's even positive but It’s really hard when all I can think of is how to comfort her disappointment.