1220 is very low for engineering and A&M does not consider your GPA at all for admissions. Since your high school does not rank, A&M will use your GPA along with your school’s grading profile that they send with you transcript and they will assign you a quartile rank: First Quarter, Second Quarter, etc. What have they assigned you? It will be on your AIS.
Your math sub score does not show a strong readiness for engineering calculus. If you did receive full admissions to general engineering, staying in would be difficult. Students have only 4 semesters to satisfactorily complete the general engineering courses. Math or physics weeds out a lot of students.
That said, A&M has partnered with several community colleges and have developed engineering academies as well as two engineering academies are admission decisions.
Applicants that are not offered admission to College Station or Galveston can be offered Blinn Engineering Academy or Mc Allen Engineering Academy. Other applicants apply directly to Blinn Brenham Engineering Academy as a back up or one of the others. Students then go on to finish their degree at College Station. Here is a list about the program and the partnering community colleges https://engineering.tamu.edu/academics/academies/index.html
The above advice from steffenberr is wrong and meaningless for transferring into Texas A&M. This past transfer cycle, Computer Science took 5 transfer students. There is a cap on seats in the competitive majors. For those that try to transfer, the must follow the Transfer Course Sheet. http://admissions.tamu.edu/admissions-staging/media/Main/pdfs-transfer2018/ENG18-ComputerSci.pdf
Current students in general engineering at A&M that are applying to a major have priority (Spring and Fall). Internal transfers have next priority and transfer students are last priority. Competition is fierce to transfer in to a competitive major at A&M.