Single cat guilt

Hey all, first-time adopting a new cat. I have never had cats before, and I am learning a lot of new things as I go.
I live with my partner in a 2-story townhome, and we adopted a cat they believe to be just shy of being 2 years old. She had kittens and all of her kittens got adopted long before we came along.
She is play, play, play, all the time. She wants to be the center of attention always, and while she can be cuddly, she definitely has her boundaries and is still warming up to us. She would rather sit and observe than be in your lap, type of thing.
When I tell others about how her energy can sometimes be overwhelming, everyone in my general vicinity starts to pressure me into getting a second cat for her. Vets, the shelter staff, my friends, you name it. There’s pros and cons to it, but honestly I’m mostly scared because her tag on the shelter said she can be “reactive towards other cats”.
We have a pet bird in our office that we have also had forever, and she cannot be allowed into the office. When she is, it’s under a watchful eye with the cage covered. I always feel bad she cannot behave in the same room as him, but instinct is instinct. I also despise the idea of having to fend off two cats from him instead of one.
My partner works from home and we spend our workdays in there, coming out every hour or so to come downstairs and play with her. If we got her a second playmate, she wouldn’t have to wait for us.
She has been getting more restless the more she settles in. More midnight zoomies, getting into things she knows she shouldnt, meowing incessantly when we are in the bathroom. Hard to tell if it’s just her pushing boundaries or not though- we’ve only had her for a month.
I’m mostly worried that we will get a second cat and she will DESPISE it. If that happens, we’re basically screwed. Our townhome is tiny, 800sqft, and with one room already blocked off permanently, we’re losing even more space. We just wouldn’t have the space to set up two separate areas for them.
She has plenty of toys, automatic play places, windows, and high areas to perch on. I am just so scared she is bored, and as a new pet owner, I’m really scared to have to handle two cats with likely two different personalities at the same time. I’m already struggling with my first one.
Am I overthinking it? Can you tell I have anxiety? I don’t know what to do!