firstly, congratulations on your successful completion of your uni course.
now on to the other issues you've outlined. whilst i cannot give 'the solution' in terms of advices, i can perhaps outline perspectives that you may or may not have considered. please take all of which follows as autistic rambling and thought.
i'll deal with each issue under broad umbrella categories, almost like a venn diagram as they insect, so perhaps best to consider them as gestalt rather than absolutely separate.
1. anxiety - being autistic, one's anxiety stems from the stimulus issues eg. over-stimulation, sensory overload etc. as you mention, the unfamiliar heightens or exacerbates sensations of anxiety. it often helps to at least be aware that what we experience in terms of anxiety is 'normal' for us. yes, that doesn't much help with the anxiety, nor stop it, as we are sensory beings, but it does at least help to know /why/, and then not turn one's thinking in upon oneself in a 'there's something wrong with me, people don't like me because xyz'; this distorted self-perception can be very damaging so it is best to be aware of the pitfalls and not fall into them. a fear of being judged can feed into this, and i will deal with that aspect later on...
2. the social ideals - one must be aware of the false ideal when it comes to life and self. the false expectations created by the idea that there is a perfect blueprint to follow when it comes to being a 'successful' person is a social construct and a lie. this gives rise to the sense one is 'missing out' on something, and 'life is passing by' because one has not achieved a benchmark. the tickboxes of this false social construct place unnecessary pressures on individuals to achieve that which is unachievable eg. success, a perfect partner, a perfect homelife, a perfect job, happiness etc. these are false ideals, and it is false thinking. it is a trap, a pitfall, and one that many people fall into. the result is this pressure to achieve that which is unachievable, and when in that mindset, the added pressure creates an exhausting effect on the individual. it's like a dog chasing its own tail; one just ends up going round in circles and berating oneself for failures which are irrational. so throw away the idea away.
3. other people and the dating game - consider for one moment one's expectations,
a) in regards to oneself
in respect of others.
now ask the question: what do you want?
this question can be applied to a) and b).
if disparity exists between a) and b), there will be incompatibility present (evidenced by factors such as feelings of frustration, anxiety, sense of failure, etc)
want is a variable.
in order to resolve/balance the 'self' equation, one must reduce the frequency of variables. this can be done by addressing:- the 'wants', (and variables inherent therein).
it is therefore important to identify whether 'self wants' are derived by
i) external factors
ii) internal factors.
'external' factors include the social ideals outlined in 2. above, and are false expectations imposed upon the person; they are false ideals, ideas, and will create incompatibility in thinking and being. 'external' factors also increase variables. the result is that one then exists in a perpetual state of irresolution; one becomes stuck and cannot move forward; one's thinking turns inwards; one seeks constantly for a state of peace and security which seems ever illusive.
'internal' factors include self-defining ideals and arise out of one's own /natural/ pre-dispositions, thoughts and abilities. these are true expectations as they stem from one's true nature - in our case, our pre-dispositions underpinned by our autistic abilities.
resolution of the a) variant, 'wants', and 'factors' means:-
removing any ideas which are non-compatible and stem from external 'false' factors and expectations
identifying and understanding 'internal' factors and 'self'.
"ultimately, i just want to feel content, happy and secure in myself..."<---i think you already know the answer and what i have outlined above is already there in the back of your mind. it is almost, and i will make a leap here, as if you need to give yourself permission to throw away the 'tickbox' social identity external factors you are aware you are subject to, and instead, define your own identity.
if you /want/ a girlfriend, and that is all you want, perhaps you need to think more deeply about what that 'want' /means/. we are a strange (and i mean strange in a gentle way) mixture of independent almost solitary nature yet simultaneously have an intrinsic need to give and share. i see it as a polarity, in that we want to touch, but prefer not to /be/ touched, until we can trust and feel safe with whom we are around. it's a fine balance, in finale, and one which can be achieved as long as one stays true to oneself, i think. one will then naturally gravitate to compatible environs which are in turn, inhabitant by compatible individuals.
like all things in life, truth is effortless, and should be effortless. anything else is false.