Hi and welcome to the tree @Mummysaurus
Agree with Sara, microfibre is not what you need, not on its own anyway! You need to get some hemp and or bamboo, personally I still use microfibre on top as it absorbs really quickly then have hemp / bamboo behind it. I would suggest trying some different sorts and seeing what works for you. I actually really liked having lots of different types as then I could customise nappies for what they were needed for. In terms of layers, it is really a case of trial and error, most of my hemp boosters were 6 layers then I'd add a MF one which was 2 or 3. It just depends on what material you are using and how thick each layer is so it is really hard to say!
Honestly if you have a heavy wetter then pockets may not be the best everyday nappy for you anyway. Fitteds with a cover (PUL or wool) would probably be a better option for you.
Brand wise, the other girls will have a bit more up to date knowledge than me but I think the Little Lambs bamboo ones are meant to be quite good value. I actually made quite a lot of mine, I just bought a metre of hemp and if you can sew a straight line you can make boosters!
Please ask any other questions you have!