??? about layers/breakage

Hello all,
I trimmed my ends the other day and saw that my the hair from my crown does not meet the longest hair on the lower half of my head. Is this natural layering or breakage? The top half also kind of thins out as it gets to the ends. Should I trim the top half bluntly to get rid of this, get layers cut by a hairdresser to prevent further breakage, or cut all my hair to one length so it can look full and healthy? any info on this is helpful.

thanks
caralexis