Hi Maddie,
I know how you feel. I was in a similar boat to you in terms of grades and put myself off from applying for doctorates because I didn't think I stood a chance. I've known people who just scraped getting a 2.1 and are successfully doing doctorates. Depending on the unis you are thinking of, some places will place an emphasis on grades while others look at you holistically. They will look at your grades (some unis invite you to share circumstances like how your health conditions/financial responsibilities may have impacted your ability to do better - this sometimes is added in the additional information section of applications). They will also look at your motivations, your experience, and your research interests.
Don't write yourself off because of not doing as well as you wanted to. You still managed to get a 2.1 even under those circumstances - you should be proud of that!
If you haven't already, start looking at doctorates that you feel you'd be interested in and start doing some research on them, have a look online, on here, even FB groups, to see if you can connect with anyone who has done the doctorate you're thinking of doing. Reach out to the academics at these unis and see if they'd be willing to chat to you too, they can offer some more advice on the process, and anything else you may need to do to give yourself the best chance to succeed.
You got this! 🙂