I think it is so personal. We tried for 6 and a half years to have a second child. We spend thousands on treatment both IUI, IVF and IVF with donor eggs. At the end I realised I was so fed up of needles and the we had no money left for treatment. Stopping for me was one of the best things I have done.
In your shoes I would evaluate what is really important to you, is it having a biological baby and being pregnant and all that or being a parent full stop. Then think about whether you can handle some of the issues that having a child who joined your family by adoption might bring. You are obviously in a marriage or partnership so talk to your DH/DP about what they feel they want.
I would make a lot of lists and revisit all this over a period of several months while still trying to conceive. If after all this you feel you want to know more about adoption I would go to an information evening/morning/afternoon whatever with a local or county council or voluntary adoption agency. Perhaps more than one if that helps.
Personally, I would also say that for me it was important to know what my chances of conceiving were so we had tests and checks and were doing all this with a fertility clinic. We also had counselling as part of the clinic, both to see if we were OK about using donor eggs and also part way along when things were not working. MANY people will not want to do IUI or IVF or donor eggs and many will not spend six years trying. I am almost certainly not typical in this.
Whatever route you take to parenthood I think it is important for it to be:
Considered (carefully over a period of time, no need for snap decisions)
Consensual (if in a partnership you and your dh/dp need to agree)
And to be super cheasy it will be:
Costly (not necessarily in terms of money but in effort hard work, testing etc)
and
(I have run out of 'C's) WORTH IT
For me fertility treatment was worth it as it was part of my journey to becoming a mum to a little girl (by IUI) and later part of our journey to becoming a mum to a little boy via adoption.
Feel free to ask me anything here or by pm. (If you do not get a reply here then do pm me as I don't look on these boards as much as I used to).
All the best.