Is it possible to come back to God after backsliding, living in sin and even mocking God at times or am I damned to hell?
Yes it is possible!!! I was saved and baptized in 1973 and when I came up out of the water I was instantly filled with the Holy Spirit and I loved everybody. At that point I was a baby Christian only 6 or 8 months old, when I received a church hurt. After I got church hurt I decided that if those folks who gave me that church hurt were proper Christians I didn't want any part of it. Even after I had a miraculous experience when I came up out of the waterSo I backslide, walked away from God and for the next 22 years I sold drugs, did drugs, and became an alcoholic. Basically lived a life of complete unrepented sin.
But one day when my life was destroyed I turned to God and He gave me a dream. When I woke up I was delivered from alcoholism and refilled with the Holy Spirit. So yes you are not condemned.
You have had a change of heart but you don't realize that a change has occurred. The very fact that you have come onto this site and asked your question show that God is working on you. Your experiences with God are exceptional. There are so many Believers who would give anything to actually hear that still quit voice of God.
I would advice you to find a church to attend and start pursuing after God with all of your heart and might. Get some good study tools like the Strong's Exaustive Concordance and a NKJV version of the Bible and study with an open mind to the spirit of God to be giving you revelations about His word.
I noticed that you haven't mentioned anything about being baptized. There is more to making a commitment to God then just saying the sinner's prayer. When you make a commitment to obey Christ and allow Him to come in and take control of your life you need to be obedient to the commands of God. After confessing your sins and asking Christ to come into your life the very first obedient act you should perform is the be Baptized in the name of Christ.
Mar 16:16 He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
Scripture is very clear here. Just saying the sinner's prayer isn't enough. Being baptized should be your next step in starting your new relationship with God.
Act 1:5 For John truly baptized with water; but ye shall be baptized with the Holy Ghost not many days hence.
Act 18:8 And Crispus, the chief ruler of the synagogue, believed on the Lord with all his house; and many of the Corinthians hearing believed, and were baptized.
Throughout the New Testament everywhere the Gospel was preached, those folks who heard the word and believed like you have were baptized.
If you haven't been Baptized that would be your next step. Otherwise you will never receive from Christ what you are looking for. You might not have the same kind of experience like I had when I came up out of the water, but I promise that if your heart is truly remorsful when you are baptized you will find that your relationship with Christ will begin to grow some teeth. He has already blessed you with a little bit of His presents. Just think how much more He will bless you by being obedeint to His will in your life by getting yourself Baptized.
Out of all of the replies to your post only one person mentioned Baptism and they weren't instructing to be baptized. God doesn't care how you come to Him, He just wants you to embrace HIM and His son and turn your life over to Him.