So tired of trying :(

I'm honestly just so tired of trying. We enjoy the sex but it's the emotional toll of the BFN every month. Next month will be a year of trying and in June our little guy turns 4. I'm worried about the age gap between him and whenever his sibling happens. 
I'm even starting to get mean thoughts when people on Facebook or glow announce they are pregnant 
:( I know it's not nice and try to squish them but it's always the 1st things to pop into my head.
I'm being referred to an gyney but all my blood work and ultrasounds have been fine. Hubby still needs to do his sperm test but we got pregnant the 1st time when I had an iud in.  
I know I should also be thankful I have one as some people can never even get that far. It's just I feel like I'm missing that last piece of the puzzle :(
I'm sorry for the rant/emotional post I just needed someone to talk to and I have my besties but they've all had no issues so I don't feel like they get it.