I have already done math methods last year, this year im doing english, spec, chem, physics. Do you think i should do further or is it just really boring
If you're happy with your methods score from last year being in your top 4, then don't do further (unless you want to it for some reason), just focus on current subjects. Reason being is that you can't have 3 maths subjects being counted in your top 4, so you don't really benefit much plus getting a really high score in Further ( 48+) may be harder than you think even you are a strong student.
If you happen to be aiming on the really high end of the spectrum (99.00+), doing a sixth subject is useful to gain a few extra aggregate points.