Not being able to stand at the sink to wash up due to balance issues or pain won't score any points because (bafflingly, I've always thought) ability to do housework is not considered as part of PIP. But if you can't safely stand at the sink, I would have thought the same applies to standing at the hob, and the worktop for chopping and peeling. Even if your son doesn't generally help you with the cooking, PIP is about the help you need, not what you get.
The washing and bathing activity is about washing your whole body and ability to get in and out of an unadapted bath or shower. So if you can't get in and out of a standard bath without assistance, you could score 3 points even if you could (theoretically or actually) get out of a standard shower. Grab rails for support or balance or a stool for sitting in the shower would be considered aids. You have to demonstrate that the aids are required and not just preferences; best way to do this is by giving descriptions of what has happened on occasions when you haven't used the aids. But you can score points for all activities even if you don't need aids or assistance, if you can't perform the task reliably (safely, to an acceptable standard, repeatedly, and in reasonable time).
For dressing, needing to sit does not often score points because lots of able-bodied people might sit while doing this, especially for putting on socks and shoes. But I think a bed or chair can still count as an aid in some circumstances. A shoe horn can count as an aid, if you need (or would benefit from using) one of those for at least one if not both of your feet(?). That might be more for people who have difficulties with their hands, I don't know. Just an idea.
From what you've written here I would think you have a case for scoring some points across both components. You need 8 for standard and 12 for enhanced.