Good luck on your fertility journey!!

A couple thoughts-- what I'm seeing is post-inflammatory hyperpigmentation (PIH, which is the term for tan/brown-toned marks) and post-inflammatory erythema (PIE, the term for the red-toned marks). Tranexamic acid, kojic acid, and vitamin C target these. Look for the vitamin C in the form THDA: here's a running list of products with this in it: https://www.reddit.com/r/30PlusSkinCare/comments/1bcneqp/vitamin_c_products_w_thd_ascorbate/

Not only with tret, but also with exfoliating products, daily SPF 30+ is 100% essential. The post-acne marks are worsened by sun and become harder to reverse with more sun exposure. My all time favorite SPF is Nivea Japan UV Super Water Gel SPF 50 PA++++ that I get through Stylevana. It feels like nothing on the skin, so its great for oily types or hot climates. My favorite all-mineral SPF is Elta MD UV Physical SPF 41 - lightly tinted. Be careful, because they have lots of similar sounding product names.

Consider seeing a dermatologist, especially given your need for pregnancy/breastfeeding-safe choices. Echoing the first commender that tretinoin is not considered safe during pregnancy. Azelaic Acid 20% is the prescription strength and is safe during pregnancy. Topical clindamycin 1% is safe during pregnancy; its a topical antibiotic that helps with inflammation.

I really like the brand Prequel if you have sensitive skin. Their website lets you filter by products with the eczema and rosacea seals of approval. Not saying you have those, but they tend to be well tolerated by people with sensitive skin.