When I conducted user interviews however I did not find any problems or patterns, the only finding seemed to be people prefer paper and pen so that idea is done.
I think interviews are a great approach to find some inspiring problems to try and solve with design. What kinds of questions are you asking them? Are you able to dig into answers and unpack things in more detail?
My wife and I use a shopping list app, a shared list synced on both of our phones. When one of us goes to the grocery store, we tell the other to ‘update the list.’ We’ve been actually using this app for about 3 years now or so.
It’s interesting to me that the app works for both my wife and I because we are such different shoppers. I go at 4AM or so whenever possible, when the place is deserted. My wife loves going on Sunday afternoon when the entire world is there and lines are long. We rarely go together because she doesn’t like the pressure to “hurry,” which is understandable, and conversely I like to plan my route as efficiently as possible so I’m in an out: produce, canned goods, coffee, then get perishable stuff (meat or dairy, frozen etc.) last before checking out.
Something else which the app hasn’t yet solved is whether certain things on the list refer to the same thing or not. Last time I was at the store, I saw she’d added “oatmeal containers” to the list. Does that mean instant oatmeal cups? If so, which? So that necessitated some discussion, and she said “Well, I know what I meant!” Which is great but doesn’t help me if I just happened to be at the store.
And conversely, I’ll put “six pack of beer” on the list, and I am pretty agreeable about types of beer but since she doesn’t drink it at all, she’ll grab the first type she sees and it may not be good.
So our solution isn’t perfect yet obviously.
Anyway I shared all of this because I think if you can get your interview subjects to open up and “core dump” like this I’ll bet you can find some potentially useful things to design app features around.