Firstly - a LOT of mums don't have enough supply, so do not feel bad about not being able to feed, it is not your fault if you have tried everything you could. Do not get into depression, do not starve your baby, it is not healthy for you or your baby for you to do either. Formula is not end of the world, yes breastmilk is better but it is also a question of what are the important things in life that matter and whether that benefit really matters that much - to put it bluntly, there is a much higher chance of getting hit by a bus than suffering from anything breastfeeding could have prevented. Secondly - have you tried all the ways to enhance supply? Water being the most important one, along with oats, fenugreek, etc (lots of material on this topic) - do not follow old wives tales of no-water, etc. you have to drink lots of water! thirdly - keep the efforts seperate, it might be you are not producing because baby doesnt know how to latch properly - try pumping as samantha suggested and keep that up, while keep trying to get baby to latch, so your body will keep trying to produce while your baby can learn to drink from bottle or breast.
You can try to direct latching your baby. Baby's suckling motion is the most powerful pump to stimulate your milk supply. Just to share, I had very low supply for my baby no.2 as I don't have enough rest daily, I only managed to pump 20ml each sides which was very depressing and finally I resorted to formula milk since baby don't want to latch too. I took 1 month to train my boy to latch on again when he turns 4.5months, I managed to do it and my supply returned fast and furious! Since then, I managed to breastfeeding my boy direct latching until he turns 2 years old plus. What I did to teach my baby to latch back was: - i feed him milk from bottle first and switch to my breasts. Prior to that I try to pump a bit to have a let down first. I have tried a lot of positions with him and found a position that he likes. During the latching, I will squeeze my milk out (baby who used to bottle feeding prefer fast flow). After he knows how to suckle (took about 1-2werks), I don't offer milk bottle anymore and direct latching.
Have you tried pumping or are you purely latching? Try power pumping.