Baby’s weight bumming me out

Feeling a bit bummed out. Bub’s weight fell into the 50th percentile at birth (3.68kg) , then he lost about 100g but regained it all by day 7. All to be expected. I was told this was normal. He gained 380g in the last two weeks. However last two weigh ins he’s fallen into the 25th percentile even though he’s steadily gaining weight. I’m being told it’s normal but I’m still concerned, and feel like I’ve messed up somewhere. He is pretty much exclusively breastfed. We introduced formula for a night feed at about week 5 or 6 so my partner could help with feeds. He had diarrhoea while adjusting to it, but seemed to be fine after. I saw the GP about this and they weren’t concerned. I was 3.2kg when I was born at full term but am definitely taller than average and bigger than average women. Hubby was a chunker as a kid! Am I bummed out over nothing? I feel like I’ve internalised so much from different people saying I didn’t have enough milk for him in the early stages. Maybe I don’t and should have supplemented sooner. I feed on demand. Should I supplement now? I’m just super bummed out over this.