I don’t believe those to be the main red flags. I’d read some credible resources and have a chat with your GP if necessary. I believe it’s things like very early speech etc but have a google.
All if the things you're describing are normal baby behaviours. My LO has only just figured out crawling in the last week, and it's not even considered a possible concern unless they still haven't managed it by 12 months. The rocking is a really common stage pre-crawling! Screen time has no effect on autism, so if he enjoys it or it helps with your routine, then there's no reason to stop. As for eating, before 12 months food is just for fun and exploration anyway. All babies are different and some are just less interested in eating. Once they hit the year mark they tend to become more interested as they start to seek their nutrition from the food rather than milk at that point. My TikTok has done the same with the videos, but there is a reason autism generally isn't diagnosed until about the age of 5 - because before that, it's hard to know if it's autism or normal child behaviour. Only when kids are a bit older do the differences start to become more obvious. Please don't worry!
Very normal behaviours and wouldn’t use Tiktok as a source of reliability. And like @Amy said things take time with some babies and they all debate different paces etc and food is not the main thing at this age just for fun. Don’t worry about it, but if you feel like things continue for a long time like several months then I would speak to the HV.
A lot of that is normal behaviour, my eldest used to splash until the tub was nearly empty, was delayed with crawling walking etc he’s 19 now and not autistic. Sensory seeking is normal development.