How do I ask for a raise, and how much should I ask for?

Hey guys, so I’m coming up on my 90 day mark at my new-ish job. I’m going to be asking for a raise for the a couple reasons. My job is currently medical assistant / medical secretary. I was hired on as STRICTLY a medical secretary at $17 an hour and was basically told all I’d be doing is handling the phones, and charting. As in taking faxed notes and putting it into patients charts. Very quickly, that changed. I’m not necessarily mad that this happened, but I also don’t expect to stay at the same pay when they’ve basically changed my job by drastically increasing my workload and putting a lot of new, important stuff on my plate. What has changed since I started?

1. I now room patients, reconcile charts, and handle referrals and orders. I was not originally what I was bought on to do. I was told in my interview I’d kinda be doing everything but this.

2. I help with prep, breakdown, and sterilization of all medical equipment when procedures are done in the office. This is not something I was bought on to do. This is also a fairly big undertaking. Time consumption wise. Because they want me to still do everything else.

3. I manage other people in my own position. I am not exaggerating when I say this, and I know to some, this may feel the case. For context, I came into this position having done it in the past and our office manager proceeded to bring in a few people without any medical experience, into this position. I have medical terminology. Some people, particularly the ones we hired, dont. Given this, our office manager, kinda without asking, put in charge of training them. Each of these 3 were told “all questions go to OP” and they moved my workspace right next to theirs. So I kind of have no choice but to manage and answer their questions, and train them. While I do my own job.

4. They want to more or less codify this hierarchy now that they’re fully staffed. This is no longer some gray area of me just wanting to go above and beyond. We have 3 doctors at our practice. They want to give each doctor their own “assigned secretary”. I am not one of those people. Why? Well, rather, what they want to do, is leave me in charge of NOBODY, aka EVERYBODY. My job, when I’m not rooming, or helping with procedures, or verifying insurances for upcoming appointments, is to comb through all the other secretaries work, and un-fuck their shit up. Notes don’t get logged correctly because the secretaries don’t have enough medical terminology. I often have to change doctors that people are seeing which incolves heated calls to the patients. The secretaries (albeit new) don’t know how to set insurances, or know the nuances, so unless I go back through, comb through these appointments a second time, and call maybe 1/3 to 1/2 of them back, and update it, the practice wouldn’t get paid.

Again, I do not mind doing any of this, but it kind of feels like they basically went and made me assistant office manager (or clinic lead) of the practice, and I want a pay increase. I think that’s fair. I guess my question is, am I sounding logical here? How much of a raise should I be asking for? I make $2 above minimum wage rn. I’m hoping for $20-21. Mind you, I’m looking a little bit ahead here. They still plan on training me to do more. Surgical authorizations. Prior auths. Stuff that usually only the office manager does. And they’re probably going to make me the person not only charged with doing it for the 3 doctors, but having to teach everyone else to do it. I also want to preface that I’m not being bitter, either. I’m more than up for the challenge of any of this. But I mean, I got bills to pay. Maybe someone in the medical sector could chime in?