I go red when i exercise, when PG i went Redder, quicker, to no detriment to me or the baby.

The abs exercises you talk about are completely fine probably until the end of the first trimester - you have to protect your abs once the baby is pressing forwards onto them. Until the baby is big enough to create a bump and put extra forward pressure (from your guts as well as the uterus) on your ab muscles you are fine to continue to work those abs

Tell your PT you're ttc, they will probably know all the pregnancy modifications they'd need to make.

Bx