I also think it must ba a 'normal' thing with this, Nikayla was 2yrs old when she passed and I had a born sleeping baby Jaylei going on 9 yrs ago, Nikayla has been in Heaven for 5yrs, I still to this day annoy my poor kids, I have a 5yr old, 3yr old and a 2yr old boy, like Dawn, my son sleeps in our bed and my hubby has a whinge every now and then but so what! Lol, he learns fast not to argue, he has said he will sleep on the couch (to call my bluff) and soon shut up when I told him "That's fine, more room for me and Tejay" Lol
But I am constantly checking the kids, if I panic, I make them stand up and say they love me or something.... It must be horrible for them, I will poke and prod them to get them to stir all the time....
It is such a hard road, but like many others have said, you are not alone....
I always hope I will get to a point where I feel able to not do it so much, but I don't see it happening... Even with my son right besides me (especially now that he just turned 2 3weeks ago, same age Nikayla was) I get anxiety that must play on my conscience in my sleep, cos I still find myself waking in a cold sweat, sitting bolt upright, looking at him and cos I am half asleep I wonder if he is really alive or gone so I move him and say "son" and he stirs, I then have a good cry to myself and snuggle him back to sleep....
I wish we never had this at all. I'm so sorry hun