without looking, you are probably a +17 because the spreads are, as you mentioned, meaningless. not based on team vs team ratings though. well, ok, ill take a look...
the sim doesn't care about team ratings - it bases it off scholarship players. the other team is a little higher than you, but with 1 less walkon, so that is a bigger difference to the sim engine than the 431 vs 423. also, the sim is 2-0, and you are 0-2. thats the biggest factor. a 100% winning % vs 0. so, that is roughly why the spread is +17. but, as you said, it is meaningless... so don't put any stock in it.