iPhone 14 Pro Max shows 37 GB in Photos even after deleting all pictures and not using iCloud

"deleted all my pictures, but storage refuses to go down: [...]my previous method was waiting till my storage got full and then transferring all my pictures to a hard drive, which worked perfectly until july when my storage problems began. not really sure what to do anymore as i cant even use whatsapp without deleting apps i need on my phone[...]"

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Thank you for the screenshot,

I. Transferring Photos to your Computer:

If you want, you could upload these photos from your iPhone to your computer, directly off of your iPhone. You would manage the files from your computer. Go here for Photos: Transfer photos and videos from your iPhone, iPad, or iPod touch - Apple Support. Once transferred, export them to an external device (i.e. flash drive), and then trash them from your iPhone.

II. Troubleshooting iPhone Storage:

Internal storage cannot be upgraded. It is what it is. So, the maximum internal storage capacity never increases, even if you upgraded your iCloud plan. Learn More here: What's the Difference Between Device Storage and iCloud Storage? Apple Support

So, what to do...

Clear Space Using my User Tips:

• How to Clear Space from your Mobile Device, and What to Clear: - User Tip. You may have too much installed, and need to clear space. So, see my user tip: 
• How to Clear "Other" in your iPhone's Storage - Use Backup - User Tip. Caches would be being used for remembrance of application use. It is essentially the same for an iPhone. You'd backup your iPhone, and then restore your iPhone from the backup you've just created. All System Data will delete.

Give this a try and then check the size of photos on the phone: Force restart iPhone - Apple Support