You should be using the 3-4-5 strings to tune to GDg. Is that what you are using?
Very thin strings they look like 3 2 1 to me , maybe wrong , you want something around the 42 32 24 gauge , I would buy a pack of cheap guitar strings and see what gauge suits you , then buy some decent ones .
My advice is to pay attention to the actual gauge sizes. In my experience you can't really generalise about just using the 5th,4th and 3rd strings from a set, as gauges sizes vary so much. I know everyone seems to say just use the 5,4 3 strings, but I thinks it's too vague, especially if you are experiencing string breakages. For example, a G string can typically be a heavy as .026wound or as light as .016plain - that's a huge variation. I use .042, .032 and .024 (or .022) for G D G tuning on a 25 1/2 inch scale. That's reasonably high tension on a 25 1/2 inch scale should be fine for 24 1/2" or 24" scale.
Are you sure that you are tuning to the right pitch? - it's an obvious question, but it's really easy to tune to the wrong note.
Is it possible that you are tuning to an octave too high? That would result in very tight strings, but your tuner would tell you that you were tuned correctly.... BTW, your guitar looks great!
I think Gitty's Open G strings are meant to tune to GDb
When you tune to pitch it means tuning to the note it should be G2 , D3 , G3 , G2 being the bottom thickest string and the top G3 is the thinnest string .
If you are on a Windows machine you can get AP Tuner from Cnet and various of the other legit software sites for free. It has several preset tunings and indicates octave, accuracy is on par with the Boss clip-on chromatic I use during set-ups.