this map definitely seems pretty interesting so i'm gonna go over some basic stuff that seems wrong to me. considering your choices of inspiration i assume that you're at least somewhat interested in mapping for competitive, and the stuff i mention will mostly be from a 6's standpoint.
Starting at last and working my way in:
Last seems immensely overscaled. for perspective, check the range on the sentry and compare to badlands, snakewater, or gullywash. the sentry at the furthest forward point of the high ground can be easily spammed out from every single entrance to last. the last should be shrunk significantly in every direction. height, width and length. that being said, the general layout seems fine, its just far too big.
a lot of the other issues that i have with last would be fixed if it were shrunk, like that it would be difficult to defend due to the variety of entrances and their distance from the point and that walking from the spawn to point takes too long.
the interstitial area between 2nd and last has an interesting layout, but it has too many shutter doors. shutters should really only exist in places where you have to block a sightline that is really,
really nasty, because it creates more problems with sentries and stickytraps than is worth. i would definitely at least remove the lower shutter and the small shutter to the left entrance
2nd suffers from a lot of the same scaling issues that last suffers from, in that it is pretty seriously oversized. the major issue is the yard, which allows attackers a massive buffer area with which to push the point and some insane sightlines across the entire area. look to gullywash and snakewater which both have similar 2nd points to this and consider the distance that you can see and how the point is protected from direct sightlines in many cases
shrinking this pit area allows 2nd retakes to have a smaller amount of ground to cover before getting to the actual point. 2nd retakes should always be easy, because leaving your last unattended is such a huge risk.
moving this whole area further forward shrinks sightlines and generally improves the flow from point to point
this area is just slightly overscaled, but i imagine it will shrink naturally if you make the 2nd point area smaller
as far as the mid goes, its definitely the most appropriately scaled area on the map, i'd focus on shrinking the other areas of the map primarily before you focus on adjusting the mid to heavily. once those issues are taken care of i think this map could really be fun, and im definitely looking forward to actually playing on it