Don't cry if your small child tells you you're a bad mother. They don't mean it. They love you to bits. It's something to smile at, not cry.
I have worn out a multitude of kitchen timers over the years. They are a mother's best friend for getting DCs out in the morning, getting homework and studying done, getting bedrooms tidied, getting showers over with in a reasonable time. You name it, a timer can help you get it accomplished.
I made the messy eaters wear bibs.
If you make dressing part of the 'leaving your room looking neat' routine then dressing isn't all there is to the business and the temptation to dawdle there can be diminished a little. Dressing can be merely the first part of a longer process. The rest could involve pulling up the bedclothes and putting the jammies under the pillow, with bidding adieu to any lovies or stuffed animals the last part of it. Everyone knows favourite animals like their room to be neat while they wait there.
Or you could alternate tasks -- DC puts on undies and shirt, you put on pinafore or trousers, DC puts on socks, you help with shoes. If front/back, left/right are issues, mark the front and the left. I put a dot of nail polish on one DD's left big toenail to match the big dot in her left shoe. The reason to mark the front (maybe sew a coloured button or bit of tape inside a shirt) is because they can see the front if they are doing it right.
You also have to break down the tasks into manageable components for the very young.
'Get dressed' may be daunting. 'Put on your shirt', 'Button the buttons, starting at the bottom', 'Now put on your pinafore' may be easier to approach.
Be clear exactly what you mean. Give one instruction at a time. Don't remind or plead - use the timer and give attention to actions that move you in the right direction.
Don't give the dawdling any attention. When you see her doing what she should be doing remark on her co-operation and any other good things you see about what she is doing. 'I like the way you got the right buttons in their buttonholes'/ 'I like the way you got your shoes on so quickly, and on the right feet too'/ 'I like the way you were so quick and neat on the loo this morning'.
You have to get into a very strict and invariable routine to combat dawdling. You have to be ready yourself to leave as soon as she is ready.
I have a specific spot where all the bags, shoes, boots and gear go last thing at night.
You should have her live with the consequences of not co-operating. But make sure it is her fault and not yours that she is late, unbrushed, dressed in PJs, arriving without breakfast etc.
(I would actually prefer to have someone eat a banana or oatmeal biscuit on the way than go without breakfast.)