Everything you are describing is a stutter or a secondary behavior. This type of impactful blocking dysfluency is ultimately more of an anxiety disorder - which is why even an SLP doesn’t understand how to address it. The more you try to hide it, the worse it gets. Your eyes flicker because your brain is trying to avoid holding eye contact bc of shame. Pretty much any technique that focuses on the articulators, taking a breath, sneakily avoiding, or VERY complex self-analysis will probably make it worse - bc it’s the equivalent of treating a cancerous mole as if it’s a regular mole. Dysfluency is a problem of anxiety and resulting tightness in your diaphragm through a mostly involuntary fear response called valsalva maneuver. The suggestions are to do the opppsite of what you are naturally doing (disclose, voluntary stutter, make eye contact, normal exhale, begin slowly, enunciate). Tim Mackesey is a SLP, PWS who learned how to speak fluently, and has a free podcast explaining all of this. It’s hard work but it will be effective in getting you to a place where you have control in speaking in a smooth way that’s pleasant to listen to.