Trichomoniasis (STD) help!!!!

So today I found out that I have Trichomoniasis, a very common curable std that shows up within 7-10 days after getting it. I have been with the same partner for almost 3 years and we have a 1 1/2 year old together in which when I was pregnant with him, I did not have this. I tested positive for it on the 5th but I recently had our daughter on the 8th and they did not tell me when I had her that I tested positive for it. I went into preterm labor and had her at 32 weeks so I know they did the vaginal swabs too when I was in labor. I know for a fact that I haven't cheated and he swears up & down that he hasnt cheated. Anyone who has had this, please let me know and help me!

1. How come I tested positive on the 5th but they didnt say I had it when I had her on the 8th ? Dont they test for the same stuff when you go into labor as when in a regular appointment? (She was born via csection thankfully so she doesnt have it) also, after I had my daughter all of my symptoms (vaginal itching) went away and has not come back. This was 3 weeks ago.

2. Does anyone know if you can get this from non-sexual contact such as dirty toilets or anything such?