Do I still have milk ?

Hi everyone, I’ve got a one month old and I have been breast feeding her since birth. But now I feel like my supply has dropped and I can’t figure out if I even have milk. I squeeze my nipples and milk does come out and when I’m nursing her she is drinking and swallowing and she seems satisfied. However today she didn’t nurse too much compared to normal, and she keeps spitting my nipple out. However she has kept the dummy in whenever she’s been fussing. Any tips on what to do to increase my supply and what is going on, should I stop the dummy completely ?