B.Y.
I have been using Dr. B's bottles since my son was born...he is now 7.5 mos. Personally, I would not change bottles unless he was spitting up or the bottle was not working for him. If it's not broke don't fix it or you will be running into other problems with new bottles other than him holding it which is superficial. Most babies dont hold their own bottles until much older...try Dr. B's WITH the handles...same gas reducing contraption....
Good luck!