I have a 5.5 week old. We sposied for the first 2 weeks - DS is small with skinny legs and the NB BSWW didn't fit at that time. I had some WAHM fleece covers that would've worked but I didn't realize they'd be small enough and didn't try them right away. So once we started CDing at 2 weeks, I had 2 dozen infant orange-edge GMD prefolds, 2 BSWW with aplix, 2 BSWW with snaps, 1 prowraps cover, 1 swaddlebees fleece cover, and 2 WAHM fleece covers. That means 7 NB covers total, however he's outgrown the WAHM fleece already and the BSWW with snaps are difficult to use cause he's so wiggly. So I'm really only using the 4 of the covers.
When we were trifolding the prefolds in the cover, the covers got poo on them often so 4 wasn't enough and 7 covers only got us through about a day and a half, but now that I'm using a snappi every time, 4 covers is plenty. In fact, yesterday he wore 1 cover all day without getting any poo on it. I think how many covers you need depends on how well you can get your prefold or fitted to fit and avoid blow-outs.
I think your stash sounds great for now. I know you said it's difficult to get diapers, but wouldn't you rather go to the trouble to get them ONLY if you end up needing them? You really can't know what is going to work for you ahead of time. In my case, I thought I would prefer the snaps, but my little guy is wiggly and I can't seem to get a good fit with snaps. I also thought I'd hate the fleece since they are so poofy, but I really loved that I could get them tight around the legs without feeling like I was hurting him. I also worried that the fleece would leak, but I guess I change him often enough that he isn't able to soak through it. I only bought the fleece covers cause they were a steal, thinking they'd be back up and I ended up really loving them. Another thing is that I got the Bummis cause I'd read good reviews, but the cheaper prowrap I picked up at a consignment sale actually fits my DS better. I do wish that I had some AIO or pockets that fit him now, but I really don't want to spend the extra money to get them since he is growing quickly and I have tons of pockets that should fit in a month or so. If you can get a good deal on them, go for it. In fact, if you think your babe will be large, some small (not newborn) or maybe even one-size AIOs or pockets would maybe fit right awayand could be worn for months.