Our almost four year old co slept with us and is now a brilliant sleeper. I wouldn't say it has always been an easy thing to do but ultimately I think for us it was worth it and the right thing to do. I don't know if it made a difference but one thing I always did was read him a story, give him his night time milk etc all in his room. He
always started the night in his own room and in his own cot. There was a period of time when he was really little that he'd last all of five minutes in his cot before going into our bed, but over time that increased and we could get to midnight or later before bringing him in.
When it was time for him to get his own bed we talked about it a lot before we did it so that he was prepared. We made a big deal of seeing his cousins' bedrooms and how they had their own beds etc etc. We took him bed shopping, let him choose his sheets etc. Then once he was in his own bed that was it. Honestly - not once since he got his own bed has he asked to come back into our bed! I couldn't believe it. HOWEVER we certainly spent many nights getting into his bed...which was ok to start with because we could fit (and to be honest, I wasn't really ready to give up the snuggles) but as he got older it got more uncomfortable. So again, we talked a lot about how he needed to sleep on his own, he could have a hand to hold but no more us getting in with him. Of course he protested and we had a few nights where he was upset that we wouldn't come in with him anymore, but we never left him alone if he was upset. Now we are at a point where we hold his hand when he gets into bed, then that's it. He gets lots of praise every morning for being such a good sleeper and he proudly tells people that when he wakes up in the night, "I just turn over and go back to sleep!"
I think you just need to decide what is right for you - it's not a problem if you are happy with the situation. The very gradual approach that we've taken was the right thing to do for us and for our son but I know it's not for everyone. We are currently struggling with DS2 but that's more to do with reflux/dairy intolerance issues and so on. I think we will need to take a different approach with him - perhaps have a mattress in our room first or something. You know your family best, you know your child best. Do what makes you happy and don't worry about what anyone else says
Your baby is SO very young still - google the fourth trimester if you haven't already x