Analyze your shots, what did you do correctly, what did you not do correctly.
You have some good groupings here, take your time and repeat this, learn from what you did wrong.
The ones that are out there, you most prob moved the gun before the shot was executed, answer here is, keep the gun up there/sights lined up for a second or 2 after the shot has been fired.
Another good mode to be in, is to relax and take your time with every shot, there is no hurry. Example, my previous target, was 20 shots, it takes approx 20 or 30 minutes to shoot this. Warming up shots, beginning shots, maybe 2, 3 or 4 tries to get 1 shot off, resting in between each attempt. Then once you start to feel good, in the zone, things start to go along at a slightly faster pace.
I like the quote from Ginny Thrasher, 10 meter air rifle champ, "shooting is a sport where you get to choose how good you want to be"
IMO, you will get to your goal stated in your original post, and hopefully get hooked on Standing in the process. Stay positive, you have 5 out of 10 shots in a good group, next time try for 6 out of 10 for good shots, then 7, etc. Do not get discouraged if you have a bad night, "All training is Good training", accept that there will be good nights, average nights, and bad nights. But it is still shooting and all shooting is Good!
Another few items to consider, all heat and how hot it gets is clothing, 1 or 2 tee shirts and then a heavy sweat shirt allows for a more stable, less bounce standing hold position, a leather glove for the front support hand is also good. Solid foot wear. ear plugs, and/or muffs.
Your idea for shooting for center of a white target is very good for beginners, you will do better with this method, then once you start to do a black bullseye, it puts more pressure on you to hit it, so you may not do as well, keep at it, it gets better.