Exercise... Which exercises are okay?

Audz ☺😉 • Mother of five... Son '00 daughter '05 b/g twins '16 son born Feb 10 '18
I have bilateral hip dysplasia and used to exercise 3 or 4 days a week. .. Since finding out I'm pregnant with twins I've been so anxious about doing too much exercise and have stopped completely except for walking. What types of exercise is okay? Any advice/recommendations will be greatly appreciated ☺