My phone won't give me Storage no matter what I do So I try to download an app but a thing pops up saying I can't because I don't have enough storage on my phone so I go to my settings and I delete some apps and some pictures on my phone but it didn't do anything it still said I have 0 storage! So I get a flash drive and download all my photos on to it and then go back on my phone and delete them all ( well all most all of them I had 1300 photos  and I deleted like 700 photos)and I go back and there was no change my pictures was still using the same amount of storage and it still said I have 0 space left! It's making me mad! Please help! ( do I need a new phone??)
Ps.i also deleted a bunch of old text messages and group chats but that didn't do anything either!
In terms of the 700 photos you've deleted, have you also deleted them from the Recently Deleted album? 

When you delete a photo/video in the iOS Photos app, it does not actually delete that photo immediately. Instead, deleted photos are placed into the Recently Deleted album. These photos will remain there for 30 days at which point they will be deleted by the system. This overall process is designed to give users the chance to recover their photos/videos in the event they change their mind, etc.

If you need to free up space immediately, you can manually go into the Recently Deleted album and select any/all items and delete them from there. This removes them from that point rather than waiting for 30 days to pass. Of course, doing this means that recovering them is almost impossible - so make sure you have a working backup of your photos/videos!