Re: dislocated elbow
No idea what your current fitness levels are. Definitely need to go seek some form of medical advice from a pro.
1. You could have natural hyperextension in your elbows.
2. Possibly you do not have a lot of bent arm strength developed.
- Most kids when learning supports at first lack a lot of bent arm pull and push strength but considering they are 2-4x lighter than adults probably decreases their risk of a similar injury even if they do have freaky elbow syndrome.
3. You may have tried the L sit after exhausting the existing strength/power surrounding your elbow.
Weird. I went through your log and I would say general pull and push strength isn't the problem and call it # 1. If this is the case, you will always have to be careful about lockout since when you lockout your elbow is at a disadvantaged position. That you continued some pushups and rows is either a good sign or possibly detrimental.
If a doc can't find anything abnormal, just chalk it up to being a freak with freak elbows and being lucky and keep it in mind.
You might want to tackle L sits without turning the inside of the elbow forward. Have it face the side of your body as this will let your shoulder take a bit more of the work than the tricep