welcome SDEMT-B. I also currently in the SD county area and a 20 y/o EMT-B. congratz. In terms of jobs, theres some information which would be useful to you. I am currently working for a Private company because it best caters to my schedule.
now for the 411; rural metro has a contract with SD to provide 911 response. AMR is also contracted in a couple districts within SD county. However, in light of san diego's interesting economic state and lower call volume, AMR and RM have both put a freeze on their hiring. Its great to try to apply but they are impacted with applications, (this doesnt mean you shouldnt apply). I am aware that AMR has about 45 emt's on their hiring waitlist, but you never know. Also they are generally much more interested if not only interested in hiring full time and only accept part time under certain conditions. I have heard mixed accounts of them not allowing part time for school but part time for fire academy, but dont take my word for it.
Private BLS/CCT companies: There are so many to choose from. For starters i know of most of them; AmeriCare, Alert, Balboa, E.R. , Pacific, Care, Schaeffer. are the ones i know off the top of my head. id rather not post anything on my opinions on these as i would like to keep that more private and i do not know if any of my co-workers are also on this forum. Just PM me or send me an email and ill gladly get back to u via email or we could meet up.