Assistant/partner in my business

Hello, amazing coaches.
I want to get some coaching on my thoughts about my assistant (which is already a T because we don’t have a contract in place and recently I have been calling her “my colleague” in front of the clients).
She reached out to me almost 1,5 years ago when I was just starting my business.
She loved my work and offered help. We agreed that I would pay her base salary (it wasn’t much) and she will get 10% of my online course sales. It was a reasonable amount then and it felt like a good agreement for both. We never agreed on her job title, and couple times when I was frustrated with the quality of her work, I used the language like “you are an important part of this work, it seems like you aren’t taking this work seriously “ etc.
During these 1,5 years she helped me a lot with many things – setting up a webpage, membership program, editing podcasts – I would give her tasks and more or less get the results. I have been paying in accordance with our agreement and sometimes even more (we aren’t talking about big numbers, but anyway).

But for a long time I have had a lot of drama about her: sometimes it takes her too long to reply, she misses mistakes, is delivering very average work, doesn’t help on the weekends, although that’s when I deliver my program.

She does a lot of amazing things, but I am in a negative space every time I think about our relationship.

I realized now after working with the entrepreneurial management course (Which btw is SOOO AMAZING. I am blown away by its quality and wisdom) that what I most want right now is a real assistant relationship, where I can ask the person to help me with all the different (including personal) things and pay a fixed salary for that.

But I feel a lot of shame and guilt. I believe if I promised something (10%) to this person- I should keep it. For life.
Because that’s why she probably agreed in the first place. She knew that I would just keep growing.

I could rehire her btw for the new real assistant position – but that again will look like a want to take away this 10Percent agreement as the business is growing.

Please help me get myself into a clean space before making any decisions.