how old should a lab be when i breed her?

Minimum of 2 years old, preferably nearing 3. Otherwise it's like expecting 12 year-old girls to be fit/healthy/mature enough to have babies. And they're not!

And please, don't forget to talk to her breeder about the stud that she would advise you to use and also, don't forget that she (and the stud) should be hip-scored. There are, sadly too many labradors limping around with bad hips through irresponsible breeding in the past, and too many young dogs are having to go through surgery at too early an age because of hip displasia.

Is eye testing not an issue in Labs too? If so you'll need to get those done too.