Interfaces cable6/0 and 6/1 are both running 64qam. Only two bonded channels down at 64 qam, the most you would get is maybe 54mbps down. You won't get anywhere close to 120. You need more downstream channels or better yet move them to 256qam.
Your upstream's are only 1.6 Mhz wide. That's very small. Have you tried 3.2 or 6.4 Mhz wide upstreams? A good mix would be two 3.2 16 QAM and two 6.4 64 QAM upstreams and at least 4 256 QAM downstream. 4 256QAM downstream gets you closer to 152 Mbps capacity. The more frequency you can spare the better. See if your plant can support higher order modulations.