I have somewhat of a similar problem - though I have a strong feeling that I'm missing something. I don't use the GTPlanet app, though, since I'm so used to Safari. The only snag I hit in Safari is when I have to edit a longer post - I can't seem to move my cursor beyond the type within the box - so I'm unable to scroll up or down to where I have to correct the typo or info.
Totally agree that the iPhone keypad is minute; one needs matchsticks for fingers. Still - the technology is advancing; we may not need fingers anymore: "Find me a washroom, Siri!"
I rarely use my phone to post. However, yanking a computer away from the addicts around my home or office is difficult - so I have to grab it when I can, especially when I need to do some 'serious' posting (photos, gifs, a long discussion, etc.)
Once again, Jordan, thanks for the sleep/home/screenshot tip. Another lifesaver! Learn something new every day - at GTPlanet of course.