Confusion with a pattern

So I’m following this pattern for a medium but I came to a problem.

Cast on 56-58-60-62-64-66-68 sts on double pointed needles size 3.5 mm with Karisma. Work 4 rounds garter st and continue in rib K1/P1 until piece measures 10 cm. Work 2 rounds garter st, AT THE SAME TIME inc 2 sts evenly on last round = 58-60-62-64-66-68-70 sts. Insert a marker at beg of round. When piece measures 13-12-13-12-12-14-13 cm inc 1 st each side of marker. Repeat the inc on every 2-2.5-2-2-2-1.5-1.5 cm a total of 14-15-16-17-18-19-20 times = 86-90-94-98-102-106-110 sts. When piece measures 45-50-50-49-49-48-48 cm cast off 6 sts mid under sleeve (= 3 sts each side of marker) and complete piece back and forth on needle (make sure to have cable row from RS after dividing piece). Cast off for sleeve cap each side at the beg of every row: 2 sts 2-4-6-7-9-10-12 times and 1 st 12-10-8-8-6-6-4 times = 48 sts left on needle for all sizes.

So starting with 58 stitches I increased 2 to 60 sts. Then increased a total of 30 sts to get 90. Then I cast off 6, then 2 sts 4 times (now 14 casted off) and 1 st 10 times with 24 sts casted off total.

So I have left 66 sts by following the pattern when it says I’m suppose to have 48. So I don’t really know whether to cast off until I have 48 or that I’m suppose to have 66 sts.

By the way here is the pattern

OK, you’re fine up to where you cast off 6sts at the underarm (84sts remaining). Then you should cast off on [I]each side[/I]:
Cast off for sleeve cap [I]each side[/I] at the beg of every row: 2 sts 4 times
So that’s 2sts x 2 sides x 4 = 16sts (total 68sts remain). For the cast off you automatically have to cast off at the beginning of the row.

and 1 st 10 times
That’s 1st x 2sides x 10 = 20sts (48 sts left on needle for all sizes.)

This way the sleeve cap will have symmetrical decreases at each edge.
(I followed the numbers for the second size.)