Hi claire!!! LOL where to start!!!
ok - breastfeeding in public is "just one of those things" these days, i have fed my last baby here, there and anywhere!!! if the baby wants a feed then theres nothing more to say!!! BUT, alternatively there are some fab breast pumps about, why not get one of those and express if you know you are going to be out and tiddler will need a feed, altho i did find that most towns etc have places that have a parent & baby room so you could feed in private. There are also some really good breastfeeding tops about too, (Ebay!!! LOL) and you could always invest in a very light shawl and just drape that over you and the bab while feeding so its discreet then!
Mixed feeding: I did try this with my last babe, but she has decided that we WONT be having any of that thank you very much!!! LOL but am glad really as i really do enjoy our time together when shes feeding, its very special. If you start mixed feeding from about 3/4 weeks i guess you would be ok as YOUR milk supply will be established and its not too long to leave it to intro a bottle or two during the night/out shopping etc either, so it would keep your options open. Keira does have juice and the odd normal milk drink now from a bottle (shes 7 months) and im due another baby in January '11 so i was getting abit worried about transition, so every so often she'll have a bottle just so i know she will get a drink when i go in to have the new baby, but i will still give her milk through out the day until she's 1 then i will cut it down to morning and bedtime milk so she gets used to it.
How come your little son doesnt sleep well? i take it, its an on-going problem since birth??? does he have his own room etc? I must admit all mine have been pretty good during the nights and have usually slept thro from about 4 months, when they start having abit of food basically. My son was the only one who woke up in the early hours until he was about 10 months old and he used to wake up at about 4/5 in the mornings, but then settled down and (touch wood!!) has been fine since - he's now 4. Please dont think me intruding - but have you tried to get his night-time sorted, specially now you have another little one to tend to soon??? stating the obvious, but it would be easier on you for sure - does OH help out?? sorry if im being nosey - its not meant in any way! I've got 7 kids altogether, if you think i can give you any help, feel free to ask away!
Hopefully i've given you some ideas re breastfeeding anyways. Take it easy & good luck! xxxx