pattern confused... help!

decreases must be made around the central stitch on every 8. (8.) 7. (7.) 7. round a total of 13 (14) 15 (15) 16 times as follows: k1 (= central stitch), k2tog, work in the round until 2 sts before your next marker, SSK.

Does this mean that I do those two decreases on every 7 rounds which needs to be repeated 15 more times? (size M, the middle). So I knit 105 rounds all together? The stitch before decreases is 66 and after is 36 by decreasing 30 Sts.

Yes, that’s it exactly. Work the decreases 15 times in total.
What is the name of your pattern?