Single mom breastfeeding

I'm a single mother living in Costa Rica. My baby is 3 wks old and I feel exhausted breastfeeding him. I haven't showered in days because he's constantly cluster feeding and is always on the boob.. my left nipple is so painful and I have to use a nipple shield with it but he fusses when i breastfeed using it. I am on the verge of giving up.. I feel like formula is so much easier you just grab a formula and they aren't clung onto you needing the boob. I feel like it would give me more freedom but at the same time I'd feel so guilty giving formula to my baby just because I'm worn out with breastfeeding. I'm sorry, just needed to get this off my chest.