It sounds like you are having a period of recharging after caring for sickly parents for so long. This is perfectly natural.
When doing this long-term one gets into the daily lifestyle mode of being their caregiver. When they are gone it is a HUGE & jarring change to one’s lifestyle aside from what is the expected grief process. I bet that you sublimated your needs to attend to their needs. You needed to prioritize them to be a regular caregiver. Now that they are gone, you are left w/ this empty feeling.
Give your self a BIG hug for being willing to help them. Now, apply this same caregiving to your self. You’re doing some useful introspection as well as reaching out to move on & this is very positive. TRUST that you will move on have a very satisfying life.
EFT might be useful. It’s an energy technique that combines tapping on energy meridians w/ positive affirmations. The free information in the below link is more than sufficient.
http://www.eftuniverse.com/index.php...11&It emid=14
A supplement, 5-HTP might be useful as a short term aid. It increases seratonin.
This isn’t medical advice or a diagnosis.
Move past grading your self harshly, feeling that you’re ungrateful. This feeling like you’ve been negligent will only further exacerbate your feeling crummy. Learning to live in the NOW, fully savoring life is a learned skill.