Tough choice. In my opinion, if you are worried and want to get the amnio, get to a perinatologist or a high-risk pregnancy OB. Rates of misscarriage are much less in the hands of someone really skilled. If you email me I can tell you of one doctor I know that is supposed to be really skilled at this.
And to help you TRY to worry less: Are you aware that
1. just being "positive" for toxoplasmosis doesn't mean your baby is in trouble? the only way to know for sure is if you had been tested prior to your pregnancy and been negative back then. Then you would know for sure that this is an infection you got during pregnancy. There's a chance you could have gotten this years ago and of course, that antibody will always be there with you but NOT affect your baby.
2. There are types of IgM for toxoplasmosis. I forgot the details but one of them TENDS to indicate an "old" infection and the other one usually indicates a "new" infection. If your OB is a good one, she can figure out which is which and use this in tryuing to determine if this might be something you got during your pregnancy.
3. One OB recently told me "in 30 years of practice I have only seen one case of toxoplasmosis and one case of listeriosis" -- so what are the odds this would happen to you if you are reasonable careful? (but yes, I know, easy to say don't worry, harder to actually do it)
I hope it turns out to be nothing and you go on to having a joyful uneventful pregnancy!