ClaraE - if your baby is feeding every 3 hours and poos are nice and yellow seedy, then you almost certainly do not have an oversupply problem IMHO...
and FWIW, I co-sleep with my baby in my bed (here's how: he's in a Grobag, with my duvet at boob level on me; the corner (that would be where he is, is completely folded back over me, but even if it flopped over, because he's up the bed, it wouldn't cover him)
DH currently on sofa bed but when we move house shortly, will carry on or transfer to cot next to bed (DS, not DH - can't write today!). I'm thinking of maybe getting a bed guard if possible so DS can go between me and it - don't know if anyone else has tried this?
AFAIK, the evidence on co-sleeping does indicate a very small additional risk but the I think the research is pretty flawed on lots of levels. And by far the biggest risk comes from smoking, by a mile.