I hear ya! I ordered April 7th. Last update I got from my SA was that I got booted to mid July (and at this point, I didn't have much faith in that date). I'd bet real money that they couldn't get me my car by end of quarter so they gave my spot in line to someone closer. Luckily my SA pulled thru and found my exact config across state, so I drove out and got it this past weekend!
I'm very happy with my choice to go with an inventory car. I'd highly recommend anyone at their wit's end with waiting, to consider the same. You may have to expand your search area and be willing to travel a bit, but I'd honestly say it's worth it. Also see if your SA can help in the hunt.
My personal experience: if the inventory car has FSD but your order doesn't, they can easily remove it. If the inventory car is the exact config you ordered (irregardless of FSD) your order price will be honored. However, if the inventory car is different in any way (color, interior, tow, etc...) you'll have to pay current price.
Best of luck everyone! The wait is brutal - I would know - but it starts to become a distant memory once you finally "get the keys"