Synonyms for "anal retentive"
I would probably go with fussy. Other possibilities include finicky, persnickety, hair-splitting, or simply the broader difficult.
"Uptight" or "Type A" (as in 'personality'.)
Less of a synonym than an allusion via an incorrect and overly literal interpretation of what anal-retentive means, but for a situation like the one you describe, you may get good mileage out of constipated.