Oh your post brings back memories, YaImStruggling. Memories I was very keen to bury. I could have written that back then...
I'm sorry you're struggling, it really is so hard to look after a baby that age. Especially when they start crawling.
Can't help you on the weight, but I see you got a lot of good tips on how to be more active.
On the issue of looking after yourself a bit more, I used to find that time passed so quickly, just caring for my son, that it'd be the afternoon and I'd realise neither of us was dressed properly and I'd scramble to get us both changed just before DH walked through the door. House still in a complete mess.
So at some point, just like you now, I decided that sucked, and I got into a pretty strict routine (we lived in a two-up-two-down terrace). I would go downstairs with him for breakfast, and immediately afterwards go back upstairs, put him in his cot and get dressed (showered in the evening when DH could watch him). Then I'd get him dressed, play some peek-a-boo or something while doing it, put him back in his cot with some toys, tidy his room, the bathroom, then we'd go downstairs until nap time. I'd just keep talking about what I was doing so DS could hear me.
Between doing it every single day in the same order and at the same time, plus keeping up a running commentary and the toys, which I changed every now and then, I managed to keep him happy enough to get the upstairs done and me and him fairly presentable. (I definitely looked more put together when DC3 was a baby though.)
Obviously he whinged more some days than others, but I felt so much better following the routine that I stuck to it anyway. Especially since we always played together as part of the whole getting dressed and tidying routine. So by the time I got downstairs, we were both dressed, the upstairs no longer looked like a tornado had gone through and we'd already done some proper play.
I wasn't too ambitious on the tidying or the appearance, but compared to before the routine it was a massive improvement for me. It made me feel so much better. Obviously I have no way of knowing what you do, or even if a routine would work for you if you haven't already got one. And if that's not for you, could you carve out even ten minutes in the morning to just spend on you by putting him in his playpen? Maybe with a Baby Einstein video on the TV to keep him entertained? My youngest two loved those videos.
I didn't know it back then, but the best thing I taught my son with that routine was actually how to entertain himself. We'd play with a toy together, then I'd put him in his cot with the same toy and he'd carry on for a little while. Over time that little while got a bit longer, and then longer and eventually I could even sit down and have a (lukewarm) cup of coffee while he played in his playpen or on the floor in front of me.