- you are technically competent
- can handle design aspects of full stack (backend, persistence, frontend)
- have enough credibility and confidence to say NO to business people
- you can lead a small team of developers (2 to 5 people)
This is the most important part. Other points you mention are about your skills and you can learn them. This one, however, is in major part about your reputation, which you need to earn.
Going a step further, I'd say you're a "Senior" as soon as people around you start to treat you as one. You can be very knowledgeable but that won't be enough if you can't prove to others that your knowledge is relevant and solid.