Well, I have only had fresh transfers because I never end up getting any frozens
I have read (in several places on my psycho-googling this week) that it takes frozens an extra few days to implant and get going. It is very likely that your beta come Monday will be in the 300 range.
The thing with betas that is universal is that the number doesn't matter as much as the facts that it is 1) going up and 2) going up at a rate that they like to see. One beta doesn't mean anything. (Well, it means you're pregnant, but I'm ad libbing off what I've read this week.) You need the 2nd beta to compare. Everyone is different and I don't think the nurse should have said anything. Over 100 my ass. Honestly? You were over 100 about 2 hours after you left the clinic this a.m., so don't worry about that part.
You are in the game. You didn't go in 14 or 15 days post transfer and get a beta of 20 and get told to come back the next day...that would be on the weak side.
did you check betabase to see their charts? betabase.info