@Sarah5648 A few thoughts:
1) As you only went live in November all you will realistically get is short notice bookings
2) Until you build a portfolio of reviews guests may not yet trust you to book for longer terms
3) Chopping and changing between short and long term lets is difficult for business rates/council tax and also for the different tax regimes between Furnished Holiday Lets and long term rentals.
4) You will have wasted all the money put in to buy STR insurance and to meet the costs of the new fire risk assessments. Also you will have additional costs for EPCs if you switch to LTR.
Finally STR revenues are way higher than LTR but the costs are also significantly more especially in the Winter.