Sounds like a winner.
1) As you found the hard way, it's always a good idea to have some boiling and cold water on hand to adjust mash temp if you miss it.
2) 50% is a normal minimash extraction efficiency.
3) Also, having extra DME on hand is a good idea so you can top up as you did. Great recovery and I'm sure it will be just fine!
RDWHAHB!
And congrats on your first mash!
