Speak to a migration agent first, many should offer an initial assessment without charge, many of the migration agents on here would be recommended.
In terms of your degree, the UK undergraduate qual on it own won’t get you registration as a psychologist here (or even provisionally registered) which is a nightmare of a process in itself. I see that it not a path you wish to follow anyway.
You say you meet the criteria for one of the other job titles on the skilled list as you get 65 points. What job title are you looking at?
There are opportunities within the field, but anything for the govt/public health under the allied health banner generally require registration with the health board. Although other job titles exist of course where registration isn’t required, or there is work in NGOs, it really depends on your experience.
So I would run your case past a migration agent (needs to have a MARA number) and then if you do qualify, also start to have a look around what’s required for permission from your ex to remove your son from the UK.