Questions about pumping after nursing, advice please!

Hey everyone, my daughter will be 1 month tomorrow. During week 2, I had to supplement with formula and breast milk due to low supply and my daughter not getting enough milk out. She was 1 month premature and we were thinking it had a lot to do with it. So the lactation consultant said to nurse, pump, then bottle to assure she was eating enough. Well yesterday I saw her pediatrician and now he wants me to exclusively breastfeed. To let "nature take its course". And I love him for that! So I've been just breastfeeding her and expressing myself to allow more milk in her mouth and to help her out. BUT he said I didn't need to pump... in my opinion I still want to pump to make sure my supply stays maintained or even go higher a little bit because I don't think I'm quite there yet. Can I nurse her then pump after? I did that earlier and my breasts were not empty. Also, if I do pump after nursing, will there be milk next time to breast feed my baby? These are probably stupid questions but I can't find answers anywhere. Thank you! I'd also like to add that even though I had to introduce a bottle so early, my daughter still latches.. I'm so proud of her! Even though she might have gotten a little lazy.