Answer
This is a definite sign of your spiritual progress. The Bhagavad Gita speaks clearly on this matter, stating that worship must be marked by complete exclusiveness (ananyata). Lord Shri Krishna Himself declares: 'Tesham satata-yuktanam bhajatam priti-purvakam. Dadami buddhi-yogam tam yena mam upayanti te.' (Bhagavad Gita 10.10) — 'To those who are ever steadfast and who worship Me with loving devotion, I grant that yoga of discernment by which they come to Me.'
Observing fasts or vows dedicated to deities other than one's own chosen Lord falls under 'madhyama koti' (the intermediate level) of spirituality. But if one observes vows only for one's ishta devata (chosen deity), that falls under 'uchcha koti' (the highest level) of exclusive devotion. The Lord has also declared clearly:
'Ananyash chintayanto mam ye janah paryupasate. Tesham nityabhiyuktanam yoga-kshemam vahamy aham.' (Bhagavad Gita 9.22) — 'Those devotees who worship Me alone with undivided contemplation — for those ever-devoted ones, I personally carry what they lack and preserve what they have.'
'Ananyata' means not worshipping any other.
Therefore, you should observe only the Ekadashi vrata — which is the vrata of Lord Hari. There is no need to observe any other vrata. For: 'Sarva-dharman parityajya mam ekam sharanam vraja.' (Bhagavad Gita 18.66) — 'Abandoning all other dharmas, take refuge in Me alone.'
And since your mind is naturally settling upon Yugal Sarkar (Radha-Krishna) of its own accord, this is your progression toward the highest spiritual state. Nothing could be more excellent than this.
Continue just as you are. You will certainly one day receive the divine darshana of Yugal Sarkar.