I was like you for many, many years - could do work and church, but couldn't do social events etc without forcing myself or had to back out completely - and I felt so much of what you have described feeling. Unfortunately I didn't identify it and it all came crashing down when I had a full anxiety 'meltdown' earlier this year, thankfully I was at the doctors at the time and am now diagnosed with anxiety (along with depression I have had for many, many years) and I am no longer able to hide behind the invisible mask I so often used to wear. I am now medicated, which helps slightly, and am on long-term sick, seeing someone with MIND and am considering private counselling. But it is going to be a very long journey for me.
It is good you have noticed these things and it would be amazing if you could get help before you possibly end up worse. Is there someone you can confide in? Are there any mental health groups in your area you can get help from or groups who can point you in the direction of help (I can't do groups as I can't be around lots of people, but I have one-to-one help), try looking at the MIND website for help, can you speak to your GP about how you feel? My GP has been absolutely amazing, she phoned me the day it all happened and we went over the options and I got medication the same day; when it was obvious there were other needs to be addressed I was immediately referred and saw someone else within 3 weeks, then MIND were in touch within two weeks of the next referral. My Dr refuses to allow me to go to the surgery for my own good as I would have an anxiety attack on the way and she saw the results of them, so she does all consultations by phone or email, this will continue until she knows I can cope with a face-to-face appointment or there is a necessity to actually see me. (With my first visit to someone else with my first referral I had an anxiety attack and she had to get a medical staff member in to help, they wouldn't let me go until they were satisfied I was ok, ended up being there an hour and a half, but they were very understanding and meant they knew where to refer me to.)
There is help out there for people who feel like you, I am receiving that help myself, but it is finding it/being referred to it that can be hard, and I would recommend looking for that help sooner rather than later. Even finding other people with the same feelings can be a help, or finding people who understand you. Often times friends and family who have never felt like you just can't understand, but there are definitely people out there who can, don't be alone in this. (I know, it's hard to go out and meet new people who can help as the anxiety stops you, but finding the right help is better in the longer term.)
Do ask me questions if you have any, I can try to answer, or if I can't help I can try to point you in the direction of someone who can help.