And realize also, that failing to keep the letter of the law will not be to your condemnation if your whole trust is in what Christ did for you on the Cross!
If you are motivated by love for God and neighbor to obey the Sabbath, Feasts, and dietary laws; knowing that you are saved apart from obedience to them; then by all means do as the Spirit leads.
But if you are in any way depending on your obedience to these laws as being your salvation, then think again: because your focus is all wrong and you have stumbled at that stumblingstone (spoken of in Romans 9:30-33, Romans 10:1-4).
The law is competing for your attention as the means of salvation in some of your minds. We must understand fully that obedience to the law is not salvational. It is the result of being saved.
Do we then seek to obey the law in order to prove to ourselves that we are saved? Do we obey the law because it is the evidence of salvation and therefore we say, if I obey the law then that proves that I am saved?
No. Our only salvation is through faith in Jesus; in being forgiven through His shed blood.
If I am going to be justified through law-keeping/works/obedience, then I must obey the law perfectly from the moment of conception to the moment of death and beyond, into all of eternity (Galatians 3:10, James 2:10, Matthew 5:48, Matthew 5:18).
The more you strive to obtain salvation through keeping the law, the more you should realize that you are a failure at doing so. If you don't have this realization, you are not being honest with yourself; and you are also not listening to the Holy Spirit at all.