Looks like you're turning into quite an attractive little figure there! Congratulations, and keep up the good work.
What you should be looking for, is subtle but immediate signs that more testosterone is being converted to dihydrotestosterone (DHT). These include hair loss, libido (sex drive as well as the urge to start some big project), and oily skin. Other signs are more body hair (e.g. more hair around your nipples, where you would have little or none if you're taking enough SP). If you notice big signs of testosterone excess, like agression, you're way too high in maca. By the time you notice slow effects, like when you're building muscle faster, it's probably too late to make a timely correction in your routine.
When you increase maca, and notice these signs after 3 days, you could increase SP. If the signs don't disappear after a few days, reconsider your maca increase. If you are just taking too much maca altogether, you will probably feel like this girl jhajha21 on pages 16, 17, and 22 of "The Maca Root Users", who just plain overdosed maca:
If you're worried about cellulite, those women there massage fish oil to keep it shiny and bubbly. I forgot who it was here on NBE, who found a cherry flavored one that didn't smell.
You could also check for signs that you're using too much SP. Conventional wisdom says that - tmi alert for the ladies! - your prostate would stop waking you up between 2 and 3 a.m. When I experimented with SP however, it did exactly the opposite. I stopped taking it altogether, years ago. You don't want too little testosterone, too: you'll have low energy, even slide towards depression. Anyway, I didn't go any further down that route, so I can't share any experience there.
Trust your instincts.