@MayDay27 19th/20th December is likely to be ovulation, so from the 14th onwards I guess. I'll wait and see what DH thinks nearer the time, it's his call. I feel the same as you about drinking, but tbh I think even if there's a chance I conceive around the 19th/20th December I'll still have a few glasses of Prosecco over Christmas Day because my dad has already started asking about whether we're going to have another and I know that a little bit of alcohol wouldn't do any harm so early on. It's just easier all round and I'm a god awful liar... literally no poker face at all.
Disclaimer - some people breeze through pregnancy with no aches, pains or struggles so don't let the next bit worry you!
Personally, I only got to 33+2 and I wasn't exactly huge on delivery day but I was already starting to feel the effort of getting myself up off of the bed or out of a chair. Also turning over in the middle of the night was really difficult. Oh, and having to sleep on your left or right side all the time was tough on my hips cause I'm not naturally a side sleeper. Walking anywhere starts getting tough too. It's basically just a huge strain on all your muscles and joints cause it's effectively putting on loads of weight over a really short period of time. Plus your body releases a load of Relaxin as you get further on in pregnancy, it's important to allow muscles and ligaments to stretch ready for birth, but when you combine that with the extra weight it just makes everything a lot harder. Also, DS was 4lb 11oz when he was born and he did not feel that little in those last few days. My poor ribs and my lungs were definitely starting to feel cramped.
Being fitter (aerobically and muscle wise) and lighter will definitely make pregnancy easier to get through. Oh and not to mention labour, that's pretty physically intensive so being fit and healthy is likely to help that side of things too.