It’s totally fine to formula feed baby while you slowly build up your supply. Not many of us are blessed with good supply. I personally had to do mixed feeding for 1.5m before I can transit to full bm.
And yes, it’s easier to hand express compared to pumping for initial days as our milk ducts are blocked. Also, it is not true that you cannot latch with an inverted nipple. I have an inverted nipple and I can still latch baby, it just takes more effort compared to the easier nipple. Try to use a nipple puller or pump slightly to “pull out” the nipple before latching. Always offer the inverted side first.
You can engage a massager to help you unclog your milk ducts, take sunflower lecithin to thin out your milk and make sure to drink more water. Unfortunately, if you want to build up supply, you have to frequently latch/pump regularly. But if pumping is taking a toll on your physical and mental health, just give what you have and top up with formula. They will grow up equally fine. Most importantly, regardless of bm or fm, fed is best. Don’t let other people’s opinion put you down.
My siblings and I are all formula fed and we turned out equally fine 😊.