A few days ago I added mulabandha and sambhavi. I quickly realized that it takes me a lot of concentration to apply them both (new additions). So I decided first to let sambhavi for what it is and focus on mulabandha. Sometimes I don't know if I'm still flexing, so I relax and flex again. Do y'all practice mulabandha while spinal breathing? Later on the day I feel my anal spincter being being flexed, then I consciousless relax it. This happens many times (no worries here, no unpleasantness, just commenting my observations).
When we are happy and comfortable with the mantra we start adding Mudras and Bandhas one at a time, they always feel a bit awkward at first but you will find that in time they become automatic.