I've had my mirena (levonorgestrel) for 5 years. Is it still effective till I get it removed in 2 months or should I use another birth control until then?

Should still be good. The duration of use of the Mirena (levonorgestrel) has been revised/extended and your Mirena (levonorgestrel) could probably remain effective for another 1 or 2 years . Be safe. Discuss your concerns with a knowledgeable gynecologist.