Toddler bed vs. Twin mattress

My newest dilemma is how to go about switching P from her crib to a toddler bed or twin bed. I have read mixed reviews about one vs. the other and am trying to figure what I should do. I also need to figure out when to move her.

The new baby is due in January and experts say not to move a baby during or right before a "tramatic" event like a new baby or moving or something along those lines. I think it would be tough during the holidays, too, when there is much going on. She is fine in her crib for now. She doesn't try to climb out, she actually likes to play in it and still has plenty of room. That is part of the reason I am considering a toddler bed. If she has plenty of leg room then why buy a bigger bed that would be totally unfamiliar territory. Plus the window for moving is from 18 months to 3 years, so I think I have plenty of time. She will be just turning 18 months on November 1.

Toddler beds take crib mattresses, which I think she would fit on until she is a few years older. I also think a bed that has sides built in will help make the transition easier because it will still kind of feel like a crib - just lower to the ground and freedom to get out. And, that is another concern. Once they switch to a bed they have the freedom to roam around their room or house. I definitely will need to get a gate because I can't shut her door. It is a "thing" for me to shut the door. I wouldn't be able to hear her and it would freak me out. A monitor is fine, but nothing like being able to sneak in to take a peek at my sleeping baby. She sleeps with the door shut for naptime, but that is only because so many trains go by during the day and shutting the door helps kill the noise.

On another note, I had my first glucose test yesterday. I am not sure how long it will take to get results back - probably by the end of the week. I am pretty sure I am fine, but unlike P, I felt pretty sick after drinking the stuff. It put me in a really bad mood, too. I am sure that is just lack of sleep, but you never know. Part of it could be that my nurse had to poke me three times to draw blood. My vein kept moving and then when she did get it the blood just trickled out. My arms are pretty sore today, which never happens.