Maybe you were grabbing at too close of a range. Try to step in and grab but staying out of his own grab range. Like right on the edge of NM's grab range. But i saw that you only really used grabs in that one round where you killed him with just grabs :D
Also options from NM's grabs:
B+G puts him pretty far away from you but if hes mind Fed and blocks you can use a 50/50 Slide or 33B mixup on him from this range, 3A+B, 11B or just footsies (step up and grab) are all really strong in this situation. A+G is one of the best throws in the game because according to Lau and Shen Rii, it gives NM +22 frames of advantage against any wakeup attack (i.e. if your opponent tries to attack from A+G, you will have 22 frames of advantage). Thus from here you can use: 33B ground hit or OKI mixup, GS B roll/ground/duck or OKI mixup, 2K against rolls and ground or 2[K] against ones who stand up and block, Lau Throw (s) if they stand up and block or delay their stand up and block and i think you can do Flapjack from ground pickup as well. And if you really want to piss them off 2A+B if they stay on the ground or roll (unsafe but fun as hell) :D. I think you can do a 1B mixup from this as well but i need to test this.
Use more B+K as well, NSS B is actually a very hard to see low especially when used in conjunction with NSS A. If anyone tells you otherwise, you are not using it correctly. Mix in GS A, GS B, Empty GS into grab, NSS A+B etc etc etc and your opponent will start blocking up.
Also if hes in soul crush position, don't even try. NM is so bad against Soul Crush its comical. His best moves are 66A+B, 44B and aB. 1[A] is strong and GS B6 is strong too as if your opponent stops blocking, it leads to a lot of damage