You've gotten great advice so far.
Here's my .02, take it for what it's worth!
Posh was six months when I got her from her breeder, at that time we did have another dog who has since passed, but he was a dane who didn't really interact with her much, so I wouldn't say they were playmates....
When I was home she was allowed "free roaming" of my very small main floor living space (kitchen living room computer area dining...it's all open) her crate is in the living room, where we mainly hang out as a family. At first when I would crate her for bed time or when I left the house (I would never be gone more than 3 hours) she wanted nothing to do with the crate-even though she did sleep in a crate at the breeders. Well, I fed her in her crate-with the door open and gave the command "kennel" with a treat every night and when I would leave. I did have to actually put her in the crate at first. It didn't take long for it click and now she runs into her crate when I say "kennel" because she knows she's going to get a treat.
Posh's crate, as I said, is in the main level of the house, and we sleep upstairs. She was an angel the first night (I'm sure she was in a bit of "shock") and didn't make a peep. The second night I heard her howling and barking. I did go downstairs to make sure she didn't have to potty. I took her out to pee, didn't give her any coddling and put her back in her crate with a treat and went to bed. She hasn't barked or whined in her crate since that second day home.
I do every once in a while take care of my SIL's cavalier spaniel, who is allowed to have free roaming rights all the time and sleeps in my Sister's bed. Since, I have enough little ones crawling in my bed in the middle of the night this isn't okay at our house. I use a crate with her which I place right next to Posh's so she doesn't feel alone. The first four nights or so (we had for 6 days) she barked at night. Actually, she barks quite a bit...when ever she even starts to woof I look at her and "growl" no bark and make a weird looking face. If she doesn't stop, I stop, pick her up, gently but sternly grab her muzzle and say "no bark." If she stops, I say "good no bark." By the fifth day Lucy (cavalier) was not barking at night in the crate.
The missing you and following you is typical Hav behavior. Poshy loves my kids and my DH, but she is devoted to me and follows me everywhere. When I'm gone she pouts in her crate, usually, and even looks for me. We've had for six months...so I don't know if this will change for Molly. But, the barking and crate training can.
Are you signed up for any obedience classes? I think this is the best way for you and your dog to gain confidence.
Also, do you have a pretty flexible schedule where you can just tote her along? Posh comes with me to all of my errand stops. We hang out in the local coffee house at least a couple times a week. She gets to socialize with all sorts of people and I get out of the house. If my errands are going to take a bit more time aka she'll have to be in her carrier, I don't take her. She does awesomely in her "bag" I've snuck her in many places. I'm pretty sure the breeder didn't do this with her, she had 7 dogs...so it doesn't take long for these guys to get used to a carrier and enjoy being with you.