Possible autism or normal speech delay?

Sorry this is a real long one girls but I’m having some concerns about my 21 month old daughter. So much so that I can’t stop thinking about it all day every day. She is basically non verbal, other than ‘no’ and ‘daaah’ which means ‘all done’ or ‘more’. She used to say mama up until she was around 1 but has stopped and refuses to call me anything at all. Just makes noises when she needs me. She says ‘Dada’ though for my partner. She understands what I’m saying most of the time, I can say to her for example ‘Go get mummy another story to read’ and she will, or ‘let’s go park’ and she’ll get her shoes. Doesn’t imitate any noises or words at all. Seems completely uninterested in even trying or doing so. I go though nursery rhymes and farm animals and their sounds countless times a day but she has zero interest. If anything she gets a bit annoyed that I’m trying to get her to. Only thing she does is do a fake cough while looking at us, which I see as her way of telling a joke or communicating. She uses eye contact but she is not fond of hugging or cuddling or being close unless she is tired or sick and then will give in to being held. She is very content playing alone and loves lining up toys and blocks, that is her main jam. Loves climbing and exploring and running away! Will never hold our hands unless it’s walking up or down stairs (one of her favourite activities) She’s got good coordination and fine motor skills. Definitely got and gets too much screen time which I feel completely guilty about but only will watch Duggee or Peppa and we read stories multiple times a day, (she only loves about 6 specific books and refuses any other to be read around her) She didn’t cry for the first 6 months of her life and is a very quiet, calm and generally good little girl who has always slept through the night and I’ve never had any issues or sleep loss with her, she loves her bed. When she was a baby she was a very interactive social funny baby who would love playing to the crowd but she seems to have regressed a lot in the last 6 months and is generally mistrustful and doesn’t like/respond to 99 percent of people around her. We took her to the zoo this weekend and she just had zero interest in what was going on, showing her the animals but she didn’t want to know. She just seems like she’s in her own little world a lot of the time. She doesn’t go to crèche or see many people other than me, my partner and one set of grandparents as I only just moved countries before the pandemic so don’t really know anyone yet after having a baby as well. I am seeing some crèches next week so hopefully by august she will be in one. I just have a gut feeling something isn’t normal and have spoken to my HV who has put her on a waiting list for a speech therapist but can anyone out there reading this who has any experience with autism tell me if this adds up? I love her no matter what and just want to do the best for her. I think it’s the not speaking at all or making noises that’s worrying me the most because she’s a smart little girl. Just need some friendly reassurance or advice before I rip my hair out!