You know what, I think as long as we are in this process (however long it takes), frustration and disappointment and even depression are going to be dominant emotions... and it SUCKS. It's okay that it sucks. But it does. For everyone, in different ways. And remember, those meds might not feel like they are affecting you, but they definitely are.
The honest truth is that since starting fertility treatment a year ago, I feel like I've lived my life cycle to cycle. Everything else is on hold. I can't make plans, I can't envision a near or a far future for myself because at this point I absolutely can't expect that I will ever be pregnant, but I also can't proceed with any 'plan B' life options as long as I am literally actively tying to get pregnant. And I'm sure most people going through this process feel exactly the same way.
I think the worst time is always the first cycle (whether IUI and IVF), because it is such a big step mentally and emotionally that you might have waited for or saved up for or really fought for, and if it doesn't work, it's hard to imagine it ever working (even though statistically, the 2nd and 3rd attempt are just as likely to work, and after that they might consider additional tests or treatments that could make a difference).
The positive part is that it gets easier either way - either you're pregnant (and you totally could be, 3dpt is wayyy too early to test), or you're not, but then the pressure is kind of off, you know? It's like running a race and realising you won't finish first, which is disappointing, but then it's like, okay fine, but as long as I finish then that's all that matters.
It sucks, it's unfair, it's a huge mental and physical drain - but you can do it. You're already doing it. :)