hun, coping with a newborn and a toddler must run you ragged!

Your newborn will seem like he is constantly attached to you, feeding or being held, but remember only a couple of weeks ago he WAS! 27 hrs a day, 7 days a week, all he knew was warmth, comfort and security. No hunger, not lying alone. He's just adjusting to this new way of living.

Have you tried a sling? His feeding will settle down eventually (it sounds like it is overnight, which is great for you), but in the meantime, a lot of what he is getting is both milk and comfort from being bf. Once he has been fed and changed and doesn't seem hungry, try popping him in a sling, where he is still close to you, but at least your hands are free to do something with your toddler.

Have you tried keeping him more awake during a feed too, to make sure that he is getting a full feed? Changing him, etc, to wake him up so that he doesn't drop off too quickly may help. When you're about to bf him, have you got some things at hand to keep your toddler amused, so you don't have to be up and down, interrupting the feed? It can be handy to have a snack and a drink prepared where your toddler can reach it, for eg. I've also heard of Mums who keep a special box of toys or activities at hand that only comes up when it's baby's feed time, so that you can have your toddler near by and occupied.

Do you have any help or support during the day?

It sounds like you are really trying hard and it will get easier. Just a caution that introducing formula at this stage may impact your milk supply, so I'd be wary of going down that road unless you decide that's what you'd like to do.