Shebalasvegas, I know exactly what you are going through. I feel like I missed out on so much with my son. I was sick from the time he was in first grade all the way through elementary school.
It is hard to pick your battles. I found myself trying to talk myself into things all the time. I agree that it is important to do fun things. Sometimes things such as going to the concert will bring you enough adrenal rush to get through it. yes you will feel horrible the next day and I did many many times, but you will have wonderful memories of the concert. It is important to pamper yourself after and not blame yourself for making the "wrong" decision. You'll feel better in a few days and one concert will not set your healing back. That being said, I did find that I had to cut out many many social functions. They were just becoming to so stressful for me that I did feel they were hinding my healing.
Caring for a 15 month old is hard hard work and also the most important. Nap when she naps, cut corners when you can (such as cleaning the house). This disease is a slow process towards healing but it does come.
Have you read the earlier post where it talks about mindset and healing? It is so so important not to blame yourself for feeling like crap but to learn to convince yourself you will get well as you pamper and crawl through the rough times.
I hope today is a good day for you. Love that little one. My sons are now taller than me and such joys. they truly got me through the roughest of days.