As you have performed Samashrayanam and Bharanayasam, you can worship Hayagriva Perumal; worshipping Hayagriva Perumal would mean worshipping of Saraswathi Devi too.
Hayagirva pooja is also Saraswathi pooja and there is no need for separate Saraswathi pooja. Swami Desikan had also written ‘devi saroja sana dharma patni’ in Hayagriva sloka.