I'm sorry you have gone through all this especially at your young age! In answer to your questions:
1. Does anyone have any idea as to how far off experiencing menopause i will be? and how I'd know?
It's hard to say. It could be many years down the road or "tomorrow." It just depends if that partial ovary can pick up the slack. With your situation the symptoms could end up being fairly severe. Some of these include inability to regulate body temperature usually causing overheating such as hot flashes and night sweats, mood changes such as depression, irritability, anxiety, joint pain, fatigue, vision changes, memory and cognition impairment, bone loss which may show up as dental changes, loss in height, being more prone to fractures.
2. does anyone have an idea of the chance of this coming back?
I don't know the recurrence rate of teratomas but there may be some info in medical literature such as Pubmed.
3. has anyone had a baby from frozen eggs?
I personally have not. Hopefully, someone will come along who has some experience (and success) with this! I did however have secondary infertility and took fertility drugs which worked.
4. what is the chance of 10% of an ovary releasing eggs?
I don't know. I do have a friend whose mom had two children with only part of an ovary (don't know how much of an ovary she had).
I wish the best for you!