Intern year I was pretty comfortable...my program is very ER heavy, which was equally helpful for getting exposure (maybe more helpful since you didn't have time taken up well-child checks). I don't claim to be able to distinguish fluid behind the year particularly well in this age, but I can tell you for sure about red, bulging vs normal light reflex/landmarks.
First, I never go for ears on patients between 9 months and 3 years without them on the parent's lap. I can pin the little ones myself (and parents are less willing/capable of helping when they're small) and most 3 year olds are over the fear and you can make it a game and they'll do okay on the exam table.
I usually start by letting them play with the light. I show the light on my hand, put my finger over it to make my finger glow, then shine the light on their hand - most usually will touch it to see if their finger will glow. I *think* that makes a difference, but it may not.
The next part is actually the most crucial - you absolutely must get the parents to hold correctly. They do that, and the kid isn't going anywhere and you'll get a good look. But unless you have a really experienced parent, you really have to tell them exactly how you want them to hold. If I want to look in the right ear, I want the kid completely turned facing that direction, both feet hanging off parents lap in that direction - none of this straddling mom or dad with a leg on either side of the body. It has to do with leverage and you put those feet into free space, there's nothing to push off of.
Next left ear placed to parent's chest. The parent then needs to use their right arm/hand to hold both wrists and bring the child's body to theirs. Taking care of those hands is crucial. The left hand is used to keep the child's head against the parent's chest, allowing me access to the ear. To see the other ear, everything gets flipped - so the child get's rotated 180 degrees to face the other direction. It's a lot of repositioning, but it's worth it to have the right hold.