Hello Chris
Well done on your first post. (it's fine by the way) What an excellent weight loss before Christmas and well done for getting straight back to it! I have only being doing 5:2 for three weeks and it seems to be working fine for me too.
I wouldn't get too hung up on how long your fasts are - the whole idea is to adapt this WOE (way of eating), or WOL (way of living), to suit yourself. It seems to me (and I'm no expert) that if your primary purpose is to lose weight, then the jury still seems to be out on how long fasts should be. The idea is that fasting twice a week reduces your average calorie intake throughout a week down to a level where you will lose weight. So, if what you are doing works for you, then why change it?
Many of those people who are into this for the other, as yet unproven, health benefits tend to try to fit longer or more frequent fasts into their week because there is some evidence that this may provide an increased range of opportunities to improve aspects of their health. There are a number of people on the forum who have a great deal of knowledge in this area so look out for their posts - carorees is one of them and it is always worth reading what she has to say.
Some of us would like to do both of these things. I am hoping to lose just over a stone and reduce my cholesterol level and BMI. I hope you have entered your weight loss data on the Progress Tracker. Having a graph showing a downward trend is so rewarding!
Good luck with your new WOE. Keep us informed on how you are doing.