Subjuctive or no subjunctive?

I was writing a short essay about my past using past tenses for a class. I wanted to say that " I wasn't sure what I wanted to do" Thinking that "no estaba seguro" is one of the triggers for the subjunctive I wrote " No estaba seguro de lo que quisiera hacer". The teacher said that I should have used "quieria" (not the subjunctive) because this sentence is telling of something that has taken place long ago. Now I am confused when to use the subjunctive. The trigger says to use the subjunctive but now it appears there is more to it than that. Thanks to anyone that can help.

Hola Oscar, I am only offering my understanding of this and if I am wrong, I welcome correction. There is no change of subject, it is only talking about you and there is no subordinate clause, so therefore no subjunctive." Espero que vivas suficente años aprender español." "I" hope that "you" live long enough( enough years) to learn Spanish." Espero vivir suficente años aprender español." I hope" I" live long enough( enough years) to learn Spanish. No change, only about" me " I'm not sure about which "trigger" you are referring to, but as your teacher said this was something that occurred in the past. Saludos, Ricardo

I decided not to deal with subjunctives at this point. I know a little bit more from listening to a video recommended by someone in this forum. I watched the first one. I think I'll wait until I got a better handle on past and future tense. The word "espero" seem to be a trigger to use a subjunctive verb. It is exciting to think that someday, I will become proficient on sunjunctives as well. Right now, I'm learning on the indirect pronouns and still working on when to use them, always before the verb or attached to the end of the verb.

Oscar, it's awesome that you are already writing about your life in Spanish. Can't wait to do that to. I just want to continue with the lessons and see where it leads me.

Ricardo and Aurora, Thanks for your comments. Learning is fun!! Oscar

Aurora: the object pronouns are a challenge to me too. My understanding is that the pronouns can precede the verb (which really challenges my English-centric mind), or they can be attached to the end of a verb if it is in the infinitive form. Hopefully I'm not oversimplifying. Dan

"Thinking that "no estaba seguro" is one of the triggers for the subjunctive ..." Oscar, I think you'll find that the 'trigger' is expressed as "No estar seguro ...", and is meant to apply only to some circumstances - eg. the present tense. Rules can rarely be comprehensive. Rules, by nature, are for learners. They rarely account for everything a native speaker might say. But I'll admit I would also have (apparently wrongly) used the subjunctive here.

Thanks Raymot. That helped put it in perspective!