Breast Refusal

My baby is nearly 8 months old and started teething approximately one month ago. Since then she has been extremely fussy on the breast while feeding, gets distracted easily, constantly latches on and off, will only take one breast occasionally, and I'm lucky if she feeds for 3 minutes total. She does this for majority of her feeds during the day. She still feeds twice during the night, and will take huge amounts during these feeds, but even occasionally these are becoming fussy also.

Up until these last few weeks there have been no feeding issues. Solids were introduced at 6 months and her interest in the breast did start to dwindle then, but there was never any fussiness associated with it.

So I'm wanting to know if this is a normal stage? Is it most likely due to her teething? I'm returning to work in a few weeks so will be transitioning her day feeds to formula anyway, so would it be recommended I don't persue with breastfeeding and just transition now? I'm really wanting to mix feed when I do return to work but am worried with these recent events that she's becoming uninterested and this will not be an option.