I did my first pregnancy and im the same as you with hygiene lol very ocd about my mouth I had a dental check up recently and found out I had two very small cavities and cried lol! Haven't had any but the one when I was a child.anyways I thought it was bc I was so sick work hyperemesis first pregnancy and not eating etc I haven't experienced it this pregnancy and have been very healthy. But that Durant like your problem lol so id suggest more calcium maybe?
I actually lost a tooth with my second baby and I'm terrified I'm going to lose another this baby.
Its not common but can happen, inflammation and bleeding gums is very common. Did you know brushing to much is almost as bad as not brushing as you will brush away your enamel and your gums which may be some of the cause for your loose teeth. I recommend brushing twice a day and flossing is not necessarily needed daily. Also do not scrub heavily anything that can be removed with brushing can be removed with gentle circular motions. See if this helps gums cannot grow back but you may see some improvement :)
I did not have loose teeth but was eating a croissant when I was in my first trimester and the fork hit my bottom front tooth and it chipped off. I was devastated since like you I take a LOT of pride in my teeth. Needless to say I got my tooth fixed and was put on calcium supplements by my doctor. With that said may be you need to increase your calcium intake.