safe co-sleeping in bed

[gizmosmama]

I'm a new, unplanned co-sleeper and would appreciate any advice on making it as safe as possible for my 4mo.
I've read up on the guidance for safe co-sleeping and we tick all the boxes but I think I need to adapt the bed as DS is starting to wriggle. I did consider a co-sleeping crib but I think DS is getting a bit too big for one of those.
The main things are:

1. There is a gap between mattress and headboard, any suggestions on what to put in it?
2. All the bed-rails I've looked at say from 18 or 24mo, e.g these. Anyone know of one suitable from birth?

Also would appreciate any other advice/tips from the experienced co-sleepers out there.

I co-slept with my 3, and I always had their head on the crook of my elbow. If they wriggled away it woke me up. I am a light sleeper when I'm breastfeeding though (which I was when co-sleeping) - not sure that would work for me otherwise.

I coslept with all 3 of mine, when little I always slept on my side, arm out, legs bent forming a little area for baby to fit, babys back to me. As they get older they would turn and bf on their own. They never moved much away from me until about 6 m. I had the crib next to my bed, pushed up against the wall hard with no way of slipping down inbetween so that formed a safety barrier.

I'm cosleeping with my almost 1yo and have since birth. We had him in a bednest until 4mo, then moved him into our bed having had too many disturbed nights trying to get him to sleep in a cot while ebf in the night. I bought a Purple Daisies bed bumper to stop him easily rolling out of bed when he was on the edge (I sleep on my side with my underside arm kind of above his head and bent round the top of him as he never liked sleeping in the crook of my arm. I swap sides to bf in the night, so sometimes he's in the middle between DH and I, other times at the edge). The bumper worked really well for us to stop him rolling over the edge but is no good for crawling babies. I haven't used a bed rail, and I suspect the age recommendation is because there's likely to be a small gap that a very small, non-mobile baby could get wedged in.

We then set up his cot minus one side for a while and tied it to our bed frame, with a blanket plugging the small gap between our mattress and his cot mattress. We set it up when I felt he needed his own sleep space. Then he started crawling and standing up in the cot so we all moved to mattresses on the floor which is where we are now.

A big baby blanket tightly rolled or a long pillow should be good to plug the hap as long as its not loose or easy to slip out onto the mattress.

Good luck with your cosleeping adventure, my DH and I love sharing our bed with our DS :)