The Perfect Fit series can be read in any order. While they are numbered to be in chronological order, the references/cameos in each book are minor and there is no downside to reading them in any order you choose.
Perfect Formation
Book 1 (m/m/f)
Novel (57k words)
Released: 3/11/09
Blurb, excerpt and purchase links
Perfect Alignment
Book 2 (m/m/f)
Novel (87k words)
Released: 6/27/14
Blurb, excerpt and purchase links
Perfect Stranger
Book 2.5 (m/f)
Short Story (13k words)
Released: 9/1/14
Blurb, excerpt and purchase links?
Perfect Addition
Book 3 (m/m/f)
Novel (88k words)
Released: 6/16/18
Blurb, excerpt and purchase links
Perfect Fit Books 1-3
Released: 6/23/18
Purchase links