You didn't really have that few cells. Probably on the order of 20-40 billion depending on which viability calculator you are looking at. When people refer to few cells they are normally talking about culturing millions of cells out of a bottle or something. You're fine.
It may need more time but it may be there is some temperature stratification in your setup. Is there a fan or anything? If the ambient at the bottom is 34, the top of the keg could be significantly warmer.
I wouldn't pump it up to 14psi at 34 degrees unless you are looking for 3 volumes CO2, which is a little on the high side depending on the style. It takes a little while to carb up if you are doing the set it and forget it method. I'd just give it some time. Also, how are you measuring that temp?
I think, even with the insulation, my probe reads a combination of ambient and wort temp. This really dampens the yo-yo effect. The temp sticker on the side of the carboy reads pretty darned constant, within a degree or so. Obviously the center of the wort may be a little bit different, but I'm...
Do not rinse Starsan. That is not the culprit and that defeats the purpose of starsan. If you are concerned with chloramines, drop 1/4 of a campden tablet (which is potassium metabisulfate) into your 5 gallon batch at the start. Skip the bleach.
You're right. It absolutely is 6 of one, half a dozen of the other. However, this whole conversation started with:
Speedyellow is right. You don't NEED multiple packs of liquid yeast. Are there times when it might make more sense to buy multiple packs? Maybe, but that depends on the brewer...