Stretch marks & stretched out skin

4 weeks PP with horrible STRETCH MARKS and saggy skin :( Are there any product recommendations to help that are safe for breastfeeding? How long after havibg a baby did you continue to see skin firm up? At 4 weeks PP is tgis the skin im stuck with or is there hope it might keep firming up a bit. Im not having too much difficulty with weight loss... It's my skin that's upsetting. Thank you!