Which of the following sentences is/are grammatically correct?
Of the correct ones: what is the difference in meaning?
Are there other (more correct or more precise) ways to express the same meaning?

1. Being 19 weeks outside the womb my baby has learned to grab things.
2. Having been 19 weeks outside the womb my baby has learned to grab things.
3. Having been being 19 weeks outside the womb my baby has learned to grab things.

The answers to What is the difference between "being" and "having been" in this context? don't help me because:

• The sentences in the linked question do not include a period of time and mentioning periods of time changes the tense usage.
• The sentences in the linked question imply causal relationship whereas my sentences imply temporal relationship.