It depends on what your goal is. If your plan is to become an academic, the real goal is to publish a lot of papers and get grants. Depending on your exact mathematical specialization, "proof-writing ability" is only loosely coupled to those career incentives.
If your plan is to compete in olympiads, then it's a different kind of goal. Unless these competitions require "showing your work", I think they incentivize remembering a lot of different tricks more than they do being able to present clear and rigorous arguments.
And if you're thinking about bailing out of academia and earning a living in government or industry, again the incentives are different and rarely really require proof.
So is it an XY problem based on unfairly comparing yourself to some ideal that doesn't exist, or are you seriously envisioning a likely future where your current abilities are going to be a major barrier to progress?