Spiritual progress is possible - but it may be almost invisible to others in terms of behavioural change; especially when judged by the highest standards of behaviour.
This, I think, it part of what Jesus meant when he said he had come to save 'sinners'. He mostly meant that he had come to save (those who would 'follow' him) from death and loss of the self; but he also meant that those saved from death would always be breakers of God's laws.
(I understand this 'breaking of law' to mean that we behave in ways that conflict with the divine motivations of God's creation, in which we all dwell. Any verbal description of 'laws' is necessarily a partial and distorted model for explaining disharmony with creation.)
And that it was part of being-saved to know that we personally are a breaker of God's laws - and in a situation where the breaking of any single divine law at any time (no matter how apparently 'trivial') is 'just as bad' as breaking many of God's laws most of the time.
(In other words, there can be no salvation by perfect adherence to God's laws; because not only is it impossible in practice - but also in theory; because the belief that it is possible to live in full accordance with God's laws is itself a breaking of God's laws!)
Therefore true, significant spiritual progress should not be measured - Is Not measured, by God - in terms of quantitative adherence to the degree of behavioural compliance with divine laws. It is measured in terms of our knowing what God wants of us, and therefore knowing when (nearly all the time!) we do not live up to this.
Since what is wanted is not at the behavioural level; we cannot monitor spiritual progress by perceptual means. Which also means that it is extremely rare that we can monitor the spiritual progress of others (although such monitoring can, to some extent, be done for those persons we love and know best.)
In other words we must (must) be able to monitor our own spiritual progress and to do so by the standards and in the way that accords with what God wants.
This is possible because we are all Sons of God. Which means that we all have in us something of the divine.
The situation can be 'modeled' by stating that there is in each of us a real self that is also divine, and which therefore knows what is in-accordance-with God's ongoing creation; and what is not.
So - it is spiritual progress to know that we each have a real and divine self; and it is further spiritual progress to be able to discern the evaluations of our own real and divine self.
Even more progress comes from the choice that inevitably arises when we discern that our own choices and actions are going-against the laws of God/ the harmony of divine creation: the progress comes from our choosing to take the side of God and creation as our highest aspiration.
It is certain that we will Not be able to put this discernment into action - we cannot align all of our behaviours with God's laws and God's creation: in other words we are always going to be lapsing-into sin, again and again; and we will be unable to prevent this.
We may align perfectly with God for a moment or two; so we can know what this is like and can choose - can want it.
We will always - soon - lapse back into behaviours that fall-away from this known-ideal.
But it is genuine spiritual progress to be able to discern from our real self; to distinguish the real self from the many fake selves that fit-in with the demands of this mortal world; and to make that recurring choice For God.
So do not despair!
Spiritual progress is possible even for the worst back-slider (and we are all back-sliders - without any exceptions).
Judge your-self as you are judged by God; not as you are judged by Men.