21 month sleeping issues

Wondering if anyone could have some insight as to what’s going on with my 21 month old when it comes to sleeping. For the past 2 months, we have been having trouble getting her to sleep through the night. Before that, she had been sleeping through the night from about 13-19 months old. The whole first year, she never slept well. So starting around 19 months old, she began waking up in the night and taking hours to go back to sleep in the night. Then she started fighting bedtime and began to climb out of her crib. At that point we got rid of the crib because of safety concerns and switched her to a toddler bed. We began having to stay in the room with her while she was going to sleep, but she still would eventually wake up in the night. I should note that before we switched her bed, we had started letting her sleep in our bed or with my husband in our spare room while she was still in the crib, because she would take so long to go back to bed that we started letting her sleep with us, just so we could get some sleep. I’m currently 32 weeks pregnant and not sleeping well as it is, so my husband has been dealing with her at night. So after 2 months of this, she’s now waking up an hour after being put down for bed at night, so my husband or I go in and put her back to bed. She will then continue to wake up every hour or 2 until my husband gives up and just lets her sleep in the bed with him. From then on, she will not wake up the rest of the night and wakes up around 6 the next morning. She goes to be around 7 every night and usually naps from about 11:00-12:30 every day. She has a sound machine on in her room as well as a night light. She isn’t waking up scared or anything, at least she doesn’t usually cry, so I don’t think she’s scared. She just gets up and goes to the spare room and stands by the bed and wakes my husband up. We really are getting tired of this and want to fix this before the next baby is here. We don’t want to have to be up with 2 kids in the night! Any help would be appreciated, thanks!