It would be a good idea to get an SG now, so that you can make sure this is safe to bottle whenever you do decide to do so. Plus, that will allow us to estimate the alcohol % for you, which is good to know.
Also, if it's sitting on sediment right now it might not be a bad idea to rack again soon, it's been quite a while and racking will help speed the clearing process.
BUT - on to the question you actually
asked to be answered
... I love oak. But, I love it playing a subtle roll, and it can be easy to over do, especially in a traditional mead (or in the case, a nearly-traditional, as I from personal experience that tea will be a pretty subtle influence in there, which could be totally great).
Until you know what you're getting with oak it can be difficult to work with in such delicate batches. If you go with oak then use cubes or spirals, not chips or powders/extracts.
I would start with 1/2 oz of oak cubes, the lower the toast the better in my opinion (but if you like smokeyness then ignore that opinion!), and start tasting it after 3 or 4 weeks, tasting every week. As soon as you're sure you can clearly detect the oak in the aroma and taste of the mead, I would rack off the cubes. At this point the oak is probably "too much" but after a good 10 months or longer it will fade into the background and become more integrated.
That's just my take on it though, others will have differing opinions of course. Another option would be to test out oaking on a smaller batch to learn about it before jumping into a big batch!