A HSG is a tubal x-ray (its a very useful test to have done) and no injections into veins are involved at all. Dye is carefully inserted through your cervix to see what the uterine cavity looks like and to see if the fallopian tubes are patent (open).
"I'm thinking I may just leave it a bit longer.
This is fatalistic on your part. But how much longer exactly?. You may not have a child of your own at all without any medical assistance. The subfertility may not be yours alone, your H may also have male factor problems. Without investigative tests you won't know and you won't be any further forward.
"Maybe we'll get pregnant without?"
A triumph of hope over experience. Your phobia of needles is really ruining your life and may well stop you ultimately from having a child of your own.
"And if not, we can still adopt".
I just can't face all these medical procedures".
Again this is fatalistic on your part. Its not at all easy to adopt.
Your case is one of the saddest I have read on here in a long time.
First and foremost you need to overcome your very real phobia of needles. Your GP should refer you urgently to someone who specialises in conquering such fears. What is it about needles that makes you so afraid?.
Ask your GP more about the needles used during the tests. I have had more fertility tests than I care to mention and the only time I saw a needle was for blood tests. Your GP telling you that you could not handle it is irresponsible. You need treatment for your phobia, the GP should actively be making enquiries about this. Treating phobias as well does not cost a fortune in monetary terms.
You cannot ultimately let your fears, and they are understandable fears, rule your life.