Don't beat yourself up. You are doing the best you can and, unless you have absolutely NOTHING else going on in your life, mistakes will be made. I broke routine yesterday and walked my dog at a different time and somehow slipped and forgot to feed him dinner. Until nearly 9 p.m. I have never done that in my 35 years of animal care and I felt like the worst owner on earth! I abused myself terribly, not stopping to think I have just returned from 6 weeks of caring for an ill parent on the mainland (i'm an islander) and am recovering from fatigue, stress and sadness.
Just having these tiny creatures in your care is stressful, requiring a change in routine, more chores, intense attention. You and your husband sound very caring. Give each other a smile and, when you get through this time, reward yourselves (maybe a double scoop of really delicious ice cream and a nice walk or favorite old movie?) You are doing a good job.