We have all made mistakes like that. I know I have.
I commend you for showing your mistake to others.
If I could offer you some advice for the next time you try this,
The little girl is adorable, but she is a distraction, trying to make a video while drilling is a distraction, trying to spray lubricant is a distraction. I would have both hands on the drill bit and make sure you sight the angle you are holding the drill to make sure you are in line with the existing hole. Have your oil galley plugs out so you can look in the galley to see when the drill has reached the galley so you do not drill too deep.
When you start to drill, the beginning of the hole has uneven material
Because you are going in on an angle, do not try to go into the existing hole until the drill has had a chance to start into the hole squarely. I have always used a 5/16 drill without issue.
You could use a reamer that is less prone to wander. Drills can and do wander off center. The most important thing is to sight the drill from multiple sides before you get in too deep to make sure you are in line.
Hopefully it will go better for you next time. I have always maintained that any engine work always requires your undivided attention, no visitors, no beer lol, and good lighting.