It might be helpful for you to find someone to talk to about meditation. From what you have written I can't see any real problems but it might be good to be able to talk it over with someone in 'real space' (as distinct from 'cyberspace').
Don't be anxious about the period of time you sit for, or anything else. If you are anxious the important thing is to stay forucessed on the anxiety itself, to be aware of it without trying to justify it or judge it. 'Seeing things as they are' is an important part of the path. Everything has a story to tell if you know how to look at it.
If you experience discomfort, try and stay with that. Learning to put up with a bit of discomfort is another part of the path. The reason it is good to sit in the customary position is because it isn't too
comfortable. It can seem really uncomfortable to begin with but a lot of that is in the mind. Like everything else, make the discomfort the subject of meditation.
I have written some brief instructions on meditation posture here
. I hope you find them useful.
It is a discipline which takes patience and persistence, but if you can stay with it, it is well worthwhile.