Well. She hasn't got a clue what you've strung around her neck, or why it's there. Or why she can't run about and do what she wants which she almost certainly has been doing for the past few weeks.
And garden practice is invaluable, but bound to go wrong as soon as there's something more exciting about.
Don't let her learn to pull, it'll make it even harder to teach her not to. As she is so tiny, keep on going with the garden training over and over again. And then up the distractions and keep on going.
Take some really favoured treats - the smellier the better and to teach on lead walking decide which side you want her on, and stick to it. Keep the lead short, so she is by your leg and jolly her along, holding to treat to keep her focused. She won't be able to focus for long, but make sure she does. If she wanders away, stop and make her concentrate on you again. If she pulls, a sharp Ah-ah and stop. Get her attention again and off you go.
It will make no difference at all what lead/collar/harness you use. She will still pull until you teach her not to. That walking nicely on the lead is the only option. I hate all types of gentle leader type things - they are a sticking plaster for a horrible problem.
Don't try teaching lead work on the way to a walk - it will go very wrong! And on no account use an extending lead - it will give a very conflicting message ie that she can pull sometimes, but not at others. Keep the lead short, and on one side only. Don't allow criss crossing or stopping to sniff or anything and you'll be there in a trice. I walk 4 labs together on my left hand side and ALL their leads are completely slack all the time.
And I'm thrilled to hear she was off lead straight away and it went well. Brilliant news.