In English, your problem is at the intersection of two muddles which makes the answer complex.
Firstly, there is a long standing issue with the word Engineer in English. It is the only word available to describe people with a great deal of training, expertise, flair, and responsibility in very complex intellectual matters concerning the manipulation of matter and energy for a human purpose. However, the word has also been extrapolated, -- in a form of inflation, -- to any job which involves a mechanical task. Though both valuable jobs equal in dignity, a road cleansing engineer, who sweeps a road clean has a different category of job to someone who designs skyscrapers, chemical plants and mobile phones, and yet we use the same base terminology. There is no protection for the word "Engineer" in English or American law (as there is, say, for "Doctor" or "Lawyer").
Secondly, a similar issue has arisen with various informatics jobs, but with even more complexity owing to an instability in terminology (we cannot even agree what word we are fighting over. Someone whose job is to replace the toner in your printer is interchangeably with someone charged with discovering faster ways to solve complex mathematical problems to model complex materials, develop massive financial systems or model cells to fight disease. Again, jobs equal in dignity but surely differing in category.
Computer Science tends to be used for the development of systems and procedures at their most abstract: the development of algorithms, study of algorithms as a class, development of abstract designs, and so on. This is a prestigious term which is frequently raided by others doing related (but not identical jobs).
Software engineer or hardware engineer are most commonly used by those tasked with developing software and hardware, and systems administrator by those tasked with maintaining them.
Programmer is common colloquially among those who do such, though they will probably officially be software engineers according to HR. In the UK, programmer, as a job title, like some others, such as Librarian, tends to be bimodal in that they are common among very junior and very senior staff, (a distinguishing feature of the British class system being that it is largely defined by aspiration, the lack of which unites its lowest and highest members, neither of whom strive). Systems programmers are programmers who take pride in their arduous job working with operating systems and other low-level bits and bobs.
Informatics is rare on its own (sadly) but increasingly common in combination with a scientific discipline (for example, bioinformaticians process biological data: once they would have been known as scientific programmers).
Specialist is not a prestigious term; avoid it for CVs and such matters. There's an odd (but not universally applied) tendency in both the US and UK to see any overly narrow domain of work as somehow a character flaw. For example, a Specialist is a low military rank, a General is a senior. (expert is an exception, presumably because unlike specialist it admits the possibility that the expertise is not exclusionary).
IT is also not a term which would fully reflect your expertise. It tends to be associated with large corporate computerised bureaucracies (risking confusion with what we would once have called a clerk), and with technicians who replace your mouse when it gets full of dust.
Only you really know the contents of your qualification well enough to know where you fit. Good luck in the minefield!
And thank you to whosoever does any of the jobs mentioned above, all of them deserving respect.
