Hi Kim, I had PT both in house and outpatient. Although I did do clamshells with resistance like you describe, I didn't get to those until about five or six weeks along.
I did clamshells first without resistance, then with at about five weeks. I started with 3 sets of 3 reps each, increasing until I could do thirty reps.
Your body is recovering, and doing so well, but my PT introduced things gradually. Starting with 30 is pushing it a bit, I think.
The thing you can trust is your body. If you are having pain from something, scale that back. I started doing the elliptical at eight or nine weeks, had pain from that and stopped it for a bit. Others have no problems at all with the elliptical and it was fine later, but my body was telling me to stop a bit, so did.
I would also touch base with your surgeon and just get their take. I had no problem calling in about my recovery.