Puppy doesn’t understand she needs to pee outside

I have a puppy and she is 11 months now. I have read many resources for the training and I thought my potty training was successful. I started with crate training since I had her (2 months), take her out every hour (now I do every 2~3 hours), I say 'outside' everytime until we pass the door, I let her touch a bell on the way, she would potty right after we go out, I give her valuable treats that she would never get inside, then I let her sniff around after potty. I work from home so I set up a pretty strict schedule for her and she's also used to that.

I though I did everything perfect and she got the idea that she needed to pee outside, so I let her free during work starting from 7 months. It was all good until I got an accident that she peed right infront of me ~2 hours since the last walk. I thought maybe she just couldn't hold it that time. Then again a few weeks later, I was caught up in a meeting so I let her play freely for ~3 hours before I took her out. I noticed she peed inside again. I checked the camera, she peed 10 minutes before my meeting ended (my door was open). She was playing her toys, then suddenly dropped the toy, didn't bother to find me, didn't bother to ring that bell, peed just a few steps away, didn't look at the pee, went back to the toy, like everything is normal.

Last week I had a third incident where I was doing laundry and she just peed infront of me again, then looked at me like nothing happened. I didn't catch it on spot so I wasn't able to interrupt her. I took her to the vet and she's pretty healthy, no UTI Or anything else.

Then I realized that she NEVER understood that she needs to pee outside, it's just I take her out frequent enough so I thought my training was successful. And when she feels like doing it inside she would just do it.

I'm really frustrated on this. Vet suggested that I go back to crate training and continue what I have been doing and she would get it at some point. But she's already 11 months, how would I know when she's ready? Now she loves being at the home freely with me and she would start whining when I put her back to the crate during the day. Would she eventually understand it at all? I know I'm a bit anxious about it, I just feel a bit down. 🙁