Firstly, the present perfect is definitely wrong here. If you are talking about a time in the past ('was' too irregular) and about dogs that you no longer have, you cannot use the present perfect. The present perfect tells us about the present time. This scenario has nothing to do with the present.
As for whether to use the past or the past perfect, it depends on whether the dogs were already used to your schedule when it became irregular (in which case you should use the past perfect) or if they became accustomed to your irregular schedule (in which case you should use the past simple),
The sequence of events, and the link between your irregular schedule and the dogs is not clear enough, I'm afraid. If you can explain exactly what happened when, we can suggest the most suitable tense.