How can I get my toddler to sleep through the night?

Hey mama’s I am at my breaking point and really need some advice/help. I am a single mom to a 3 year old girl and I’m a student and work part time. Up until about a year ago my daughter was a great sleeper she went to bed fine and slept through the night. Now for the last year she screams for atleast an hr when putting her to bed and gets up almost every hour through out the night screaming, trying to get in my bed, and asking for drinks and snacks when she already has a cup of milk and eats a decent sized snack between dinner and bedtime. She doesn’t get any sugar before bed or really even through out the day as she’s not a big sweets kid. Her bedtime is 8pm and she wakes up at 7am for daycare. She does nap at daycare in the afternoon for about an hr and iv tried stopping to naps but nothing changed. Iv also tried white noise, night lights, sleep training, a small dose of melatonin and even getting her a nice new queen sized bed. Everyone keeps telling me its a phase and she will out grow it but it’s been a year and between school and work and being up all night im exhausted and not sure what to do or where to turn to have any other mama’s had this problem?? Any advice or ideas for things to try would be extremely helpful! Even just some encouragement would be amazing because I really feel like I’m failing…