@missladybird I was reading this wondering if perhaps you had OCD and now see that you have... I am really sorry this is happening to you... I have OCD and completely understand how debilitating the anxiety and complete panic is.
Couple of things... Firstly, if the pack doesn't state an ABV (like on a bottle of wine or beer etc) then there is most likely no alcohol at all in it at all. If there is, it is probably like chucking a drop into a swimming pool - it's detectable with full on testing but not detectible with consumption.
Secondly, if there was any alcohol in there in the first place, it would have been burned off with cooking.
I know this probably won't help, or will only give you a short moment of relief before you start worrying about the unknowns again but honestly, this is the absolute truth.
Your OCD seems to be triggered by responsibility (as mine is) and I just want to let you know that you are not irresponsible - you are doing a great job. You don't have to check everything your DC consume in minute detail to be a good parent. If, and I mean IF your DC had a drop of alcohol (which I am sure they didn't) this doesn't make you a bad parent or represent a failure in care or judgement.
Please speak to your GP as soon as you can and get a referral for some talking therapies... You don't have to feel like this.
OCD is a complete bastard but you can be free of the symptoms... I had some excellent treatment on the NHS and now when I get intrusive thoughts (when I am tired usually - 2 small kids, no sleep, general chaos) I can recognise them immediately for what they are and they don't cause me any real distress any more. It is liberating after so many years of misery to essentially give the middle finger to OCD every time I can dismiss one of these thoughts and calm myself from the anxiety. I hope you are starting to feel better today.