In my day the regs said trip fuel allowing for upper winds and weather etc plus diversion fuel plus 30 minutes holding. Extra fuel was carried within the available weight limit at the discretion if the Captain. A bit for inaccuracies in weather predictions and a bit for mum !!
If you did divert and had used your holding fuel, then when you were making your approach there wasn't a great deal left in the tanks.
The decision to divert should always be made as early as possible and once the decision has been made go straight to the alternate. Never turn back and better to hold at the alternate than wait at the original destination in the hope things may get better. May not be an airlines way of priority but will sure be the safer option.
Take it from me. I have experienced this for real.
Coops