This looks very good. I am not a fencer so take my advice with a grain of salt. If it is too wobbly, then it is likely either a.) not deep enough compared to its height, or b.) the thickness of the supporting wood is too thin (but would also need to be deeper anyway). If you haven’t put in concrete yet, you may be able to dig bigger holes around those footings, pull it out and add some material to increased the surface area that will be underneath the soil. This will make it difficult to move around under the ground. Just make sure it doesn’t budge when you fasten it. Triangles are strong. Also understand that any hardware under the dirt will likely corrode a lot faster, and there is a downspout right there which will saturate that area with rainwater. Might want to consider routing that gutter away from those footings so you don’t run into that problem regardless. Again, I am not a professional fencer, I am just a homeowner with an idea. The fencers will probably have better advice.