VictoriaCrystal, hair growing in layers is not necessarily an indication that hair didn't break. If all strands are the same length, then when straightened, hair will appear to have layers because hair at the crown is starting off from a higher point than hair above the ear or at the nape. If all strands broke evenly, because they experience the same things, you'd still end up with layers for the reasons I just stated.
When hair breaks, it's the oldest ends that break. There's no way to avoid withering of ends because organic things get old and wear away. If you can keep those ends hidden as in a weave so they aren't experiencing trauma from styling or drying from the wind, then you may be able to slow down that withering. But if wearing your hair out, then your ends will wither. Since all strands are experiencing the same environmental stress, then we can guess wear and tear happens to all of them at the same rate. So if you started with layers will will end up with layers whether you have breakage or not.
Breakage doesn't always happen as one big chunk of hair, but can be as small as dust. That is why for over 30 years, I never saw my hair break but it was stuck at SL. Splits start at a microscopic scale and if you consider how skinny strands are, it's very hard for splits to get to say the size of half an inch without some of the thinner parts of the split breaking off, especially since splits don't just happen as a central tear but could be a fan of tears. And each of those arms are so thin and so weak that breakage is inevitable. Just coz you don't see it, doesn't mean it isn't happening.
Anyway, my point is, the way to know you had negligible breakage isn't because your hair is in layers but it is if you gained about 4 inches of length (assuming your rate of growth is average) in 8 months.