Oh lucky you to be able to have a personal trainer! It great to have someone push you that extra rep or that extra hill on the bike.
I can't affort to hire a professional at this point in my life, but when my boyfriend and I go to the gym together he acts as my trainer and it really makes me work out so much harder.
When I started working out after not having the energy for it in the beginning of atkins, I put on a little weight but I'm pretty sure it was water. Don't let that discourage you.