Paper lasts 2/3 years from date of manufacture including time spent on store shelf. Get flat fog after that. Long story I do not wish to explain. 7 was correct years ago, many years ago.
Working strength developer lasts 6 to 8 hours even if you bottle it up after one print and use it the next day. Low contrast flat prints.
Print in total darkness is the most easy way to check safelight. Better ways exist.
I can not see you neg and if it has enough contrast. Develop longer is cure.
If you are working from a half full bottle of stock developer, it probably went bad. I decant stock to small bottles when first opening or making.
Note on developer - I use Liquidol pretty exclusively, bought it for the convenience but keep it for the longevity.
Working strength from a print session tray gets poured into a bottle and topped off with butane. Even 2-3 weeks later it still gives max blacks. If it starts getting a little weak, I splash some more in the tray.
I start every print session testing my fix and dev with the paper I'll be using (you need to develop to test the fix anyway) using paper strips marked in time increments. Maybe not wildly scientific, but for those of us who don't get to print every day, it's been a happy discovery for me. And no more mixing powders into stock solution. It's a beautiful basic developer and as claimed in their marketing, it's very long lasting.