I think it is only when you are in the midst of the routine that you will really have the sense of what you are physically able to do and what is physically beyond what you are able to do. Obviously, you must not endanger your own health and safety or jeopardize your patients welfare by being exhausted.
It is a blessing to have churches so close to both your home and your work and I pray that they help you find a good solution.
As a priest myself, I would urge you not to be shy to consult the priests at both parishes.
Presumably, the church near your home is your parish and the pastor will have the ability, by canon law, both to dispense and to commute regarding the obligation…especially to dispense you in the first weekends or to commute it, as the pastor prefers, so that if you are unable to get to a Saturday evening/Sunday Mass in the stress of the transition, you need suffer no qualm of conscience.
For the parish so near your work, the priest has most likely confronted this very issue before and may be able to assist as, for example, having those who bring Communion for the hospital patients providing you with Communion, too, should it be that there simply exists no way for you to reach a scheduled Sunday Mass and if it can be arranged in keeping with your particular duties.
As you make the transition to the schedule, the priests should be able to assist you pastorally. Nursing is an essential vocation – as any priest who has been hospitalized knows all too well first hand. I am also very aware of how disruptive such a schedule change is and the toll it can take physically as well as the disruption to the body’s circadian rhythm that is very far reaching.