As others have said, it's mostly if not all due to seeing. The seeing from my location on the night of 6/7 May was extraordinary, so it looks like you caught some of that on 7th May, but for me most of the nights prior to and since then have been very poor indeed. I've posted my best image from 6 May elsewhere on SGL, but have included it again along with my poor 'best of the rest' since then taken 15 May to show what a difference it makes.
The same permanently mounted well collimated and cooled scope/camera combination, shooting mono RGB-RGB-RGB sequences stacked in AS3! wavelets in Registax6, derotated in WinJupos. Seeing is everything and very fickle indeed from the UK, especially with Jupiter at such a low altitude, i.e. you never know when it's going to be good. Make sure your scope is well collimated and cooled and just keep trying..., though personally I haven't been trying planetary recently due to a combination of holiday and me getting back to imaging DSOs.
Good luck, Geof