Harvesting breast milk

My midwife mentioned last week that I can start harvesting colostrum if I’m leaking so decided to give it a go today seen as I’m officially on leave from work (39 weeks)... I managed to collect a good 3ml on my first go into a sterile bottle and I’ll syringe it up and freeze it later.

However, my uterus now feels kind of heavy, maybe even a little achey... I know nipple stimulation can induce labor - has anyone had any experience with this?!!