On the physical plane 20 years is not a very long time. If you are not recieving any messages from you passed loved ones then one of two things is happening, One there is no message this "illness" you are experiencing sounds like a life lesson gone bad. And, you must pick yourself up and keep going.
The other is that your not listening to there messages. However, I don't see that being the case at all. You must also understand that there are certain things we are sent to earth to figure out on our own. Please try asking your guadian angel what is going on with you. You may not hear it with your ears. You may see it in the oddest of places but it will most certainly get your attention.
My feeling is that your life has just begun here on earth. Examine what it is that caused this illness, it is emotional rooted as are all problems in my opinion.
Loss is also a life lesson, it's what you do with that really matters. My health went to h*ll in a hand basket when my 11 week old son died, 8 years ago and I am just now returning to the living! I have learned the lesson of his short life. I now fully understand (all within the past 24 hours) why he was only here for 11 weeks and most importantly, I can finally say "THANK YOU" to him and my guides and of course God for giving me that lesson. However, I don't think, they thought I was that slow of a learner. LOL!!
I don't sense that you are leaving this earth plane any time in the near future. I don't know if that will anger you or please you. Don't give up! One day you will look back on this dark time in your life and the words I have written here today and say
"OH, I get it."
You are not alone, love is and always will be around you.
Love and Light Always.