I hope this is relevant and allowed, if not please delete.
If you can, see if there is a branch of NCT near to you. Their breast feeding counsellors will be people who have experienced successful breast feeding themselves and know the tricks. For virtually every mother, the first few weeks of breast feeding are very difficult, baby not knowing how to latch on, mother getting stressed / distressed. Breast milk production works on a feedback mechanism of supply and demand. If you add supplementary feeds the demand goes down and so does production. The trick to successful breastfeeding is 'any time, any place' - breastfed babies do not tend to have routines, you cannot rely on a 4 hour gap, or a 3 hour gap, any gap at all. During periods of growth spurts etc, demand goes up, the key to managing this is to feed on demand, make sure you get plenty of fluids and sufficient rest.
If you are feeding very frequently, which is the norm in the early days, you will be told by inexperienced people that 'you do not have enough milk'. I was told by an ill-informed midwife that my first baby, 9lb 2ozs at birth, was 'starving to death'. If she hadn't been followed on the next shift by a lovely old Irish sister, who never left my side all night after I'd tearfully asked for a bottle of formula, I would not have succeeded in feeding that baby or his siblings.
My best advice, once breast feeding is established, is discover when you have plenty of milk (for me it was first thing in a morning) and fill a bottle of milk by breast pump for when you have little (for me that was early evening) to supplement with. But in the early days and weeks try to solely breast feed as the required action for a baby to successfully breast feed (with the whole of the nipple in the mouth and a chewing action) is entirely different to bottle feeding, just achieved by squeezing the teat between the tongue and roof of the mouth.
37 years ago I was determined to fully breast feed but got such hopeless advice from midwives I almost failed. My eldest son had a few supplementary feeds whilst still in hospital and he went on to develop eczema then asthma. I was determined to fully breast feed the next two, and they had no cows milk till after 12 months old and they also developed eczema and asthma. So whatever happens, don't blame yourself for the outcome, you can only do your best.
The best resource, all those years ago, was a book by Drs Andrew and Penny Stanway, called Breast is Best. It's advice is top notch. I managed to buy a second hand copy on Amazon for my daughter in law.
If she has finished with it (she is currently expecting her third baby and having fully breast fed the other two, I think it may be sitting on a bookshelf somewhere) I will pm you and if you like, I will post it to you. We won't see her till late April.
Good luck with everything and most importantly, don't beat yourself up.