Look OP, I will tell you straight up.
I am from your neck of the woods, used to work at the old Parkland hospital. There are no guarantees. I had nearly a 4.0 in undergrad but struggled on one section of the MCAT. Didn't get into medical school in Texas, but did get in OOS. There is no guarantee that you will get into medical school, just because you are a Texas resident. A lot goes in to it. Right now, I am borrowing 45K per year at 6.9% interest for tuition, and another 25K a year at 7.9% interest for living expenses. Add that up and you will have accumulated a LARGE debt after medical school that will eat away at a substantial amount of your income.
Second, it is difficult to get residency at Parkland. I am applying for residency soon and their spots filled up quickly and they have over a 500 person wait-list. Maybe after you become an attending, you could practice there. But, to train there, is very difficult because a lot of medical students want to train in a county setting or a pseudo county-community program that gives them access to high patient acuity and good pathology. It is very specific of you to ask and use Parkland as an example. You should worry about doing well in your classes, passing the MCAT, and then revisit this topic at a later time. First thing you should actually do is to decide whether medicine is really for you. I know a lot of my classmates who, if they could go back now, would not go into medicine just because of the changes that are occurring with healthcare, the time spent away from family, the sacrifices, the debt that you accumulate, the countless hours of charting after work, etc. etc.
Find some doctors to shadow and decide if this is really for you. Then, hit the books and do well on your classes and the MCAT. If after you get into medical school and you feel strongly about EM, apply and see where it takes you. EM is becoming increasingly more competitive. Gluck.