While I haven't had anything similar to what you went through.... I've had my fair share of surgeries, etc. For me, too - it was getting my energy back that took the longest.
For me, the two biggest important things to getting energy/strength back have been eating properly and being active enough/but not too much. I have to force myself to eat many times and to make sure I'm not just grabbing something from the kids' plates - but eating a balanced meal w/ plenty of protein, etc.
Also, re: activity - it's hard when my energy level is so low or the pain is so high... but, again, I have to force myself to walk and get my body moving. I can't exercise in the traditional sense due to all my health issues - but I can walk... and I do as much as I can. Some days, it's not much at all - but I still try.
Also, after surgery, I usually make sure I'm taking a multi-vitamin to help in healing, as I have some deficiencies in that area, too.
From there, it just takes time, I guess. I know it can be frustrating..... but I hope you continue healing each day - and that your energy returns, even stronger than it was before. Keep us posted on things, Michele.
Take good care --Tina