Same problem. I'm a 38L (finally got fitted after nearly 6 mths of wearing a saggy 44G) was also a 36G before pg. I was given a support pillow called a dream genii (now from the NCT) which works really well and doesn't slide about like the crescent-shaped ones as it's anchored by a little back-cushion, as arms not really long enough to hold ds in the right place. Lying down (on side) is good for me. Rugby ball works less well for us, but only 'cos he giggles if he can see my face and then I start giggling and we don't really get far with the milk - it worked pretty well when he was younger. I have to support the boob or it just pulls out of his mouth and I did find it all took a lot of getting used to - much longer than other people seem to take to get to grips with bfing. I still have to squidge the areola to a better shape to help him latch on and to give him an airspace if they're soft. Watch out for blocked ducts where the supporting fingers dig in (I have to change my grip or if I forget stroke downwards or very occasionally use a hand pump to unblock).
Dunno if this is size related, but I've always had problems with him deliberately pushing the nipple forward (and crushing it) to slow a flow that was too fast. Ow. Used to have to keep switching from one to the other during a feed to give each mangled nip a chance to recover.
Out and about I prop him on a pillow, or a couple of baby blankets and hold the ankle of the leg he's resting on on my knee with the other hand to get him to the right height (does that make sense?). Leg goes a bit dead but he's getting quicker. Or better still I find a way of sitting cross-legged as this works much better - but is less acceptable in a restaurant!
In terms of covering up, I've finally worked out that (longish) strappy vest tops from asda or H&M under a t-shirt top work well as you pull the vest top down (and it covers up your tummy) and the t-shirt up so that it covers the top of your boobs. I don't have a hand free whilst feeding in public to cover up with a scarf or anything.
On the bra front, I'd probably go for any soft-cup bra that's big enough to start with (even if I had to go up several back sizes)as they seem much less likely to block if they're kinda hanging a bit, and then see what size they are when they settle down after a while - you might be lucky and get back into an L cup. Rigby & Peller make custom made bras - but you have to go to London and I've no idea how much they cost. There are a few other companies online if you google 'custom-made bras'
good luck - we're still doing OK at 6 months. I agree there's not much advice out there.