Nicole--
My daughter was 12 months old after my surgery--just starting to walk, and so much less active than your son, so I can well understand how challenging and inconvenient your fatigue must be.
For a while after surgery (a couple of months, I think), I had a sitter (an adult woman) come in for a few hours each morning, which gave me a chance to take long, slow walks to improve my balance, which was really poor for at least 6-8 weeks. Then in the afternoon, I'd nap when my daughter did. I had cleaning help during that period, which really helped too. Any chance that even if your current support network disperses you can book some sitter hours or a weekly (or biweekly) cleaning service, so that you can really whittle down the number of things you need to expend your energy on (and focus most of it on your toddler?)
For me, the fatigue was most intense in the first 2 or 3 months--that was really a period when I HAD to nap each day (and I'm not ordinarily a napper, even if I don't sleep the night before, etc). After that, I had returned to most of my normal activities, even if at a slower pace for a few months longer...
Hang in there--you are only 3 weeks out!