Liz24, Excellent that DD slept for you last night
As I said DS2 sleeps thru (ish) when he has his morning feed I put him into bed with us, on his front too,( I feel happier as I can hear him breath and feel him move) I also did this with DS1 and he went into his cot at 5 months and we had no problems with him, in fact when DS1 wakes in the morning, around 8 - 9 am @ weekends, we all get into bed and cuddle, have family time, it's great, then we watch a bit of tv before getting up.
My DH was a bit like you and said if we put DS2 in bed he'll get used to it, as I pointed out its only in the morning from bwtn 5.30 - 8am, it can be dealt with when he's bigger as he'll be asleep in his own bed/cot at six months,& will prob sleep thru to 8am solidly (work pending of course).
As long as they arent with you all night, its then that they get used to it and wont sleep alone, I had a friend who ended up with her DS in bed with her til he was 2 yrs, as he wouldnt sleep alone, due to being in the bed all night.
Go with what you want to, its your child and only you know what they are like.
Good luck with the swaddling, fingers crossed it helps