Like you, I was absolutely dreading breaking the swaddle habit (he was in a miracle blanket). I researched all over the internet for advice to find other mothers in the same predicament.
My baby was 11 weeks old with reflux and pretty bad gas when I decided to try un-swaddling. Part of my concern was him being sick while swaddled. My husband was away and I had had a week of no sleep. I was literally at breaking point, very emotional and sleep deprived.
My gut instinct like yours was that he was getting fed up of being swaddled, but at the same time would cry once he broke out. I also felt being swaddle was constricting him moving his legs up to release the gas. I decided that one afternoon I would try putting him to sleep unswaddled for his afternoon nap. I knew if I tried at night I would be too tired to persevere.
I had read that babies need to learn to sooth them selves to sleep e.g. like learning to walk, if we keep holding them they won't walk. The same thing with sleeping. So after a LONG 45 minutes of crying heart breaking for me, but I kept telling myself he would be OK and reminding myself of everything I had read. I would also go in and check on him touch his stomach to let him know I was there, but not talk to him or pick him up. I went in after longer intervals. His crying started to stop & start also in intervals. Then he fell a sleep for 1.5 hours !!!!
I was SURE I wouldn't be so lucky that night BUT he slept through and when I checked on him he was lying in his cot with his arms wide out and legs open. He was very content.
Now at bed time he goes to down without any tears. I would say ROUTINE is extremely important. I bath him, give him a baby massage, then bottle (then after 30 mins because of his reflux) put him down.
I would say it was a turning point for me. We are both now sleeping much better and he seems like a different baby. So much happier. Now my husband & I wonder if we should have done it sooner because he was waking up every 2/3 hours in the night. Perhaps the gas was a contributer too, which he seems to have grown out of. Although watching him kick and hearing the gas come out was very rewarding !!
Good Luck.....