Can I get some advice?

I have been ttc for 14 months now, I'm young and healthy and live a healthy and active life, I have been pregnant before but let's just say, that didn't end very well. 
​I am now trying for my second pregnancy but first baby and have been for nearly 15 months! 
​This is my first month of consistently using preseed and I'm hoping it works as imam 2 dpo today. 
​I feel so apprehensive about testing because I am so used to being let down. It will be my birthday on the 26th of this month and af is due the 23rd! So wow would it be amazing to get pregnant this month as I'm also going lanzarote on the day after my birthday with my hubby. So it would be great if af was at bay andi was pregnant! But we will see..
​If it turns out I'm not pregnant, do you have any advice on what step to take next? I began feeling disheartened months ago..