Pregnant with a 7 month old and freaky out

I found out today I am 5 weeks pregnant with our second. My baby just turned 7 months. I was wondering if I was pregnant because my breast milk supply dropped to almost nothing and my heart rate went up on my Fitbit. I am freaking out because I was scared that I didn't have a ton of time with my baby before baby number 2 comes. Also, that I wasn't able to feed my baby for a year. We are going in tomorrow to the baby's doctor, to talk about what formula I need to put the baby on. I am also a little scared about money even though my SO says we're doing fine money-wise. It just I have always worked since high school. So I feel bad not contributing money to the family. I am happy that we were able to get pregnant this time with a fertility doctor. Thanks for reading I just needed to tell someone.