Before row 3 I have 32 sts. Row 3. Inc 1, p1,[p1, k1, p1] in next st, p3tog; rep from to last 2 sts, p1, inc 1 and I’m supposed to end up with 34 sts. I don’t get how to do it and up with the right number of sts.

You should have two increases, one at each end.

The (p,k,p) in next stitch will increase by 2, but the p3tog will decrease by 2 so they will cancel each other out.