It is not only your problem. Even professional native speakers, for example, politicians, tend to forget the verbs at the end, although they are using much more complex sentences.
My experience is that this mistake makes native speakers need to think some seconds, what you tried to say. Thus, it is an ugly mistake for them, although your sentence remains so or so comprehensible.
Also note, that language teachers are very good to understand everything what you try to say on German, due to their big experience to communicate with low-level speakers. Futhermore, they are using Hochdeutsch. But the common people is not. My experience is that from about two major mistakes becomes your sentence incomprehensible for them, this verb positioning is one. And an incomprehensible sentence means the break of your communication context, and this we never want.
This is a very essential construct in German. You have no other way, you need more practice. If it really won't work in the spoken language, then do this first in writing. There are various translation trainings around, the simplest is: you have a list of sentences on your first language (or on English), and you translate all of them to German. Then your teacher checks the result.
You need to also learn to embed multiple such structures, for example a modalverb in a subordinate clause or in Ausklammerung ("..., die Sachen erledigen zu können."). The important thing is the automatization.
My (non-professional, not native speaker) impression is that your language course is focusing probably too strongly to the spoken communcation. You need clearly more experience in the written language, this is how you can practice the very alien grammatical structures. At first, construct the German sentence as if you would write a program (if you are a programmer), and do this verbally only after you are good in the writing.