Let your hips drive, not your arms, total game changer.

Man, I felt that fight with the flathead in my soul, that first spline is always a pain! For the corners, I start at one corner and pull the mesh just a little tight as I roll, working my way around so it eases in instead of bunching up.

Gotta love when the guy at the camera shop drops some ancient wisdom that turns out to be total nonsense for your film stock. Metering for shadows is great advice for slide film or digital where blown highlights are dead forever, but color negative film is the total opposite, it loves light and hates being underexposed, and your experience is proof that his rule was backwards for Portra. The real trick is to meter for the midtones, or if you want to be safe, meter for the brightest part of the scene and open up a stop or so, because negative film can take a little over but not a lot. Honestly though, blown whites on a whole roll sounds less like a metering rule problem and more like your K1000's meter might be off or the lab pushed the development, so get the camera checked too. Bracketing is fine but you'll burn film fast, and for a wedding you only get one shot at those moments, so learn your meter and trust it. Next time skip the old guy's advice and just expose for the skin tones, that's what actually matters in portraits.