First of all, Irisée has answered you in great detail and I think I only have to add a couple of pieces of data.
Ok, so, you should definitely speak with some interpreters and have your A's checked. Not that I doubt they are true A's, but it's better to be sure, than to find out they are not true A's during an exam. In the profession someone with Buglaria and English A, German B and Spanish C would be very, very uncommon, and that's why I'd advice prudence.
But for now, let's assume your languages are exactly what you mentioned, English and Bulgarian A, German B and Spanish C.
First, I have to tell you that ESIT is out of the equation. Since last year they've reduced their activity to traditional languages (Eng,Fr, Ger, Sp, Ru, that kind of thing) and they don't teach Bulgarian A's anymore. Neither do they accept Polish A, or other eastern languages.
Second, I can't really talk much about German schools, my knowledge is limited to the fact that I know some of the teachers. My impression of Heidelberg is that they have some genius teachers alongside very mediocre ones. But the most important thing is your work, so that's certainly not a fatal flaw, one can get a fantastic training in those school.
Third, have you considered English schools, for English A's? Bath, Edinborough? I hear very, very good things about Bath. But I think they demand French? You should check that out.
Last, you not having French yet prompts me to advice you to consider the school in Sofia. I know the school quite well, and I was positively surprised at the quality of the training. And it's the only one I know that will let you in without having French. Which is fantastic, since the technique doesn't change when you work with a new language.
You could go there and then add French.
You've got a very good combination, but you should definitely add French.
Anyway, i'm going to send you a PM about sofia uni, if anyone else reading this wants to know about the interpreting masters in Sofia feel free to contact me.
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