Oh question.
How do you make things 'official'? Do you put it in writing? Carve your initials into a tree? Wear each others WWJD bracelets? Have a tea ceremony with both parents? Or something else.
No need to overthink it.
This goes back to something I mentioned earlier. We often want steps, not principles. Say I'm buying, I don't know, a gingerbread house. I don't want the bakery to give me a book about the properties of the gingerbread or its relationship with the icing.

I want step-by-step instructions that tell me precisely how to assemble the gingerbread house. In that case, I don't want guidelines or theories, I want an exact pathway from "not-gingerbread-house" to "gingerbread house."
Dating doesn't work like that. Human relationships are dynamic. They don't come with step-by-step instructions. So you need principles instead.
Another example is sailing the ocean. And dating is kinda like sailing the ocean. You can't get turn-by-turn directions when sailing the ocean. I guess someone could give me some, but they would just be a history lesson of what worked that one time that
they sailed the ocean. Instead, you need principles. Like how to navigate. How to chart using the stars. How to read a compass. How to read a map, How to use a sextant. Tools, principles, etc.
So how do you make things "official" in dating? Well, you communicate. You give each other clarity. You don't give each other room to guess where you're at. You don't play games.
And, if you're not in a situation (emotionally, spiritually, financially) where you can get married in, say, the next six months, then don't be in a rush to "name" your relationship. So do some evaluating if you're both ready. Until you're both convinced that life together would be better than life apart. That's the whole point of dating. Evaluating.
That's what you want, I think. A season of real evaluation that leads to a firm conclusion about whether it's a good partnership or not.
it's not romantic to waste someone's time, is it? Date to evaluate. Evaluate as quickly as you can, but as long as it takes.