Haven’t had a long rest in 5 sessions

So my DM changed how rests work in his campaign. He made it so that long rests take a week in game and short rests take a day. As a wizard, this kind of screws me over and messes up how a lot of different spells are designed like mage armor for example lasts only 8 hours because you would normally be able to long rest in 8 hours and get your spell slots back. But his new rules make it so that I would spend all my level 1 spell slots just on mage armor if I would want to. That’s just one example but even for how wizards prepare spells too. I’m stuck to the same set of spells for 7 days without being able to change them. We probably have about 2-3 combat encounters a day and I can barely use any spells for them and we have almost died every encounter. I don’t really know what to do.

Also: No we are not running headfirst into encounters. Most of our encounters are surprise rounds against us and we almost always just run away, unless I would be able to use one spell slot to end the encounter nothing more cuz I can’t afford it. We don’t really get to do much during the rests since we have to be doing things that “aren’t too taxing” in order to benefit from the rest which makes sense but 7 days of that feels long lol.

Update: I talked to my DM, he said that he didn’t really think about how it affects some of the spells like mage armor. So he will let mage armor stay until long rest, but I still can’t change my prepared spells until after a long rest. He said that we might have to just change things as we see fit. The rests are going to stay 7days long and 24hrs for a short rest. But he said since I am an Elf I only need 3.5 days to long rest. Still long but I think it will be okay. The rest of the party is pretty new (most are playing for the first time) so they didn’t even know that in “normal” DnD games a long rest is 8 hours. I was looking at some spells though and 3rd level Catnap gives the benefit of a short rest in 10 min and I’ve never used it so I think that’s a perfect opportunity to use an uncommon spell. Anyway, thank you all for your suggestions!!