Used to vs would structural difference

Question

I have a doubt on the following question.

1) I ______________ want to be a practising doctor but now I'm more interested in research.

Options:
A. was used to
B. used to
c. would

I was going with would but the correct answer is used to.

Tips:
1.We use used to + infinitive to talk about permanent situations that are usually no longer true.

2. We do not use used to if we want to talk about how long the situation lasted.

Reference: Cambridge Grammar for IELTS

Now although I read this two tips, but still this answer is not clear to me. Is this question related to any permanent situation?

I still don't understand the reason behind the choice used to, rather than would.

Answer 1

Would and used to have very similar meaning but the main difference is that used to can be used to talk about past states while would only applies to past habits.

Want to be a practising doctor is a state of mind not a habit/repeated actions.

For more information, check this explanation at the BBC's Learning English website.