Problems with playtex ventaire?

My 6 week old has been using playtex ventaire since about 3 weeks old and they always leak the problem i have is the nipple hole is stage one and it pours out my son soaks everything it pours out of his mouth is there a different nipple i could buy smaller than stage one and also which bottle is better for colic and antigas ventaire or avent i also heard gerber has a bottle for colic i dont know any one with expirence i need a really slow flow nipple i dont really want to buy one of each bottle the main problem i need to fix is the nipple flowing to fast thank you