I think I’m autistic high functioning
Hi and welcome to the community! 
If you haven't yet seem them, you might these NAS resources helpful - they explain the main signs / symptoms / characteristics of autism:
NAS - Signs that a child or adult may be autistic (lists over 60 signs)
You might find it helpful to note down all of the signs that you recognise in yourself (and perhaps also that others might have noticed), and then include this list when talking to your GP, if you decide to get assessed.
To learn more about getting assessed, this article is a good place to start:
NAS - How to request an autism assessment
It's from the NAS's diagnosis hub, which covers all stages of the process.
For those who live in England, it also includes information about requesting an assessment via Right to Choose (which enables access to private providers who might have shorter waiting lists than the NHS, but with your referral and assessment still fully funded by the NHS).
The NAS articles include links to some screening questionnaires that you can complete, to get a better idea of whether your suspicions are correct. But you might prefer to use the website below for this. It provides a useful commentary for each questionnaire, and enables them to be completed online (with scores calculated for you), saved as PDFs and - if the results support your suspicions and you decide to seek a formal diagnosis - printed off or saved to share with your GP.
The AQ-10 or AQ-50 seem to be the most frequently used / required by GPs in support of NHS referrals. (RAADS-R might also be helpful, but recent research has thrown doubt on its clinical validity as a screening tool).
