Dieting while breastfeeding

So my 5 month old baby is still breastfeeding and I haven’t lost any of the “baby weight.” Aside from not recognizing myself, I need to lose this weight for medical reasons before we can try for another baby We’d like to start trying when this one is around a year old.

My only concern is that if I start dieting hard it could negatively affect my baby’s food source, either in quantity or quality.

Neither my doctor or lactation consultant were helpful in this regard. So I put it to you, other moms! Has anyone been in my shoes? What have you found?

Keep in my mind that I’m (deep) in my 30s and have always had weight struggles. So it’s not just going to “fall off.” It will be hard work.