I do weddings and have done so for years with all sorts of bad light.
I've come to expect that bad light during the ceremony is the rule.
I would be glad to review some of your shots and give suggestions.
I usually work the ceremony with a 24-70 and a speed light.
Except when flash is not allowed I rely on my 24mm 1.4 and 85 1.2 but watch your dept of field,
Luckily most of the wedding party is not moving so a low speed can usually work
I would definately push the ISO before dropping the speed below 100 or AP less than 2.0
The 5DIII is an extreme shot saver and I can shoot in church at 6400 with no real degredation of quality.
As far as florescents overhead, I try to turn them off if they are above the bride and groom, no amount of white balance can fix the hair once lit with the florescent.
I also have a second assist use a 70-200 from the back of he church and/or from the balcony.
I will convert to BW when I really want to keep a shot but have poor color.
You had the advantage of white walls to use for a bounce which can work in your favor.
Weddings are a unique challange and if you are not completely confortable you really need a second experienced photographer.