Starting about a month ago, it takes forever for my Iphone to upload a file when I'm trying to post a pic. I usually have to try 5-6 times to get it to upload. Nothing with the phone was/has changed (that I'm aware of), its an old Iphone 4 that has worked well for years. I'm pretty computer illiterate, so if I left out obvious need to know info, sorry, just ask.
Do you resize the photos at all? iPhones make huge images, I used to have a 4s and couldn't upload from it reliably without resizing first.
I don't know how you got by, I have never been able to upload huge files like that. I recommend using an app called batch resizer and converting everything to 1000px or less.