How to Stop Breastfeeding

Need tips on how to stop my toddler from breastfeeding lalo na I’m 6 weeks pregnant. I consulted my OB, ok lang naman daw as long as no spotting but still a risk since breastfeeding can cause contraction. My toddler is mix formula and breast milk ever since. But really need to stop him. Any tips? Thank you!#2ndpregnancy