I've traveled the world. The things we've heard about Tijuana are not true. I just returned and I would walk around most anywhere alone. It is beautiful, clean, with not so clean areas, upscale areas, great restaurants, excellent food stands. There is some trash on sidewalks in some locations, just like your hometowns or big cities. It is a large city and you will be isolated in one very small perfectly safe area.
You are taken care of and will have everything you need. I went alone. My roommate had never traveled before and she managed perfectly well on her own. Doctors can be pompus asses, and friends give you advice on stories heard from their past based on disinformation. "I heard that it is........" without any knowledge or background or personal experience.
I would go again, and recommend you join Dr. Altamirano face book page, and do a skype interview with him.
Because if you go to Mexico, you will get nothing but excellent care from an attentive, physician, care from hospital attendants immediately, clean rooms, expert service. All, English speaking. Bet your doctor cannot speak Spanish.
And to add, after leaving surgery, Ive had no pain meds. Mine was a complicated band to sleeve revision.
Plus, if your doctors agreed, they or their friends would not collect the $14-$20,000 they expect to charge.
Go, its perfectly fine, and you will learn something valuable and gain new experiences like a quiet hospital and no noise from the nurses' station all night.