Try different formula in case she is sensitive to what you are feeding her. Dairy can cause issues such as upset tummy and this can cause an infant to be fussy. I went through this. If she is old enough, give her some teething biscuits. If not, be sure to burp her a lot and try different formula, or one without iron in it (half iron, half no iron).
Take her for stroller walks or rides in the car. Read books/picture books to her.
Find a young teen or preteen to help out. That way she can get "training" while you shower, eat, etc. The baby will like the attention from someone different, and infants and small children often gravitate to older kids.
Join play groups and you can meet other young mothers and then share watching one another's babies, as well. No relatives? Reach out to Mom or MIL if possible. Aunts? Grandmothers? This is where the "extended family" helps out, but it is still workable if you find those preteens in the neighborhood, church, etc. who love babies.
If she is old enough to sit up, give her pots and pans with wooden spoons to bang on. Find small things in your drawers that are not choking hazards. Place them in a little box or container for her to pick up and play with, if she is old enough. Each day, place five or six new/different items in the box, so she is not bored. She will explore these, pick them up, put them back, turn them around, put them in her mouth, etc.
You need help of some sort. Find that help. It will be O.K.