Okay well the movement issue makes sense as to why it may take longer. Make sure will the clippers you only really remove whatever is on the nail plate don’t actually cut the cuticle off until you get more confident.
If the lashes are very long then use a medium if not stick with small
I’m now using rods instead of shields and they give a better result. Like you said don’t pull the lashes up too much, if the waterline is not exposed then you will have a better result
I use lash bomb on myself and have never had any sort of issue. I leave each step on for 5 minutes and it gives a great lift. Did you make sure you properly removed the product each time? I can’t imagine it being anything other than being over processed but then again I’ve never tinted first so...