The last six months are not for new sources. They are for consolidation and to revise what you’ve already studied — standard books, notes, current affairs, and key themes. Depth matters more than expansion at this stage.

Create short revision cycles. Divide subjects week-wise and revisit them repeatedly instead of finishing one subject and moving on permanently. Multiple quick revisions improve recall far more than one long reading.
Finally, integrate revision with regular testing. After revising a subject, attempt questions from it and analyse mistakes immediately. This strengthens retention and sharpens exam temperament. In the final stretch, clarity and repetition win over quantity.