(haven't read all the responses, so forgive if this is repetitive...)
I CD'd my son until he was age 2 & after many trials & errors with fit, leaks, smell, etc., I decided that Green Mountain Diapers Cloth-Eez were what worked best for us.
http://www.greenmountaindiapers.com/diapers.htm
(I did see someone mention sanity napkins...absolutely no need for that, plus you're messing with chemicals in the pad in close contact with his skin & reproductive parts - there are MANY links to sanitary pads not being great for women, let alone infants!!)
At the very least, you need diaper-service quality (DSQ), 4x8x4 layers as a minimum for each diaper. I learned this the hard way as well by getting 4x4x4 layers or some such. There is a major difference in the amount of liquid that can be held in a thicker-layered diaper.
It may be the diaper cover, but I would definitely rule out the type of diaper first before investing in a different cover or a completely different style of diaper altogether. Prefolds will always be the cheapest way to go, but IMO, they are also the easiest upkeep & can be used for many other things once they're "retired" from their original use. We're getting ready for baby #2 in a few weeks & I can't wait to just pull out the cloth & not have to stock up on disposables!!
Good luck! I would say I "wasted" about $100 trying out different CD-related products before settling on a system that worked for us. But it's not fully a waste since you can re-sell your items for partial price on a lot of different websites.