Seems like you use uair at the end of combos. When in fact, a nair or dair would work as well. Since he's still tumbling you might as well hit him with something has has more damage and knockback.
Also, I didnt see any off-stage edgeguarding. I noticed a few times where a simple tailspike would have done wonders. Using a fsmash to edgeguard doesn't always work. This doc didnt too too good a job on spacing with the ledges.
I use the usmash more than the fsmash, because it has much more killing power (cept for those space animals) than fsmash. I'm not sure if you were just using fsmash because doc's recovery isnt that good or what, but if you aren't going to go off stage I would practice doing so or ue the usmash for kills.
At times it seemed like you just froze, not sure if you're too fast for yourself or what, but keep moving.
Even against Marios, spamming jolts isnt such a bad idea, just make sure you don't get hit by them. If used right you can punish them for caping, but approaching only to be hit by the reflected jolt is careless.
Finally, could you explain why you tried to grab so much? THe times you did throw him it didn't really combo to anything/put him in a bad position. Against a doc I would stay generlly close to edge and toss/knock him off then do a quick tailspike to get him at <50%, but that's just my thoughts.
Feel free to comment on anything I said, I'm just learning too.