Latching issue. Of using nipple shield?

My baby is almost 2 months old .She has laryngomalacia...she was in NICU due to Bronchiolitis..while staying in hospital she was feeding with food pipe, Nifty cup..After getting discharged she was not feeding directly from breast, right now she is only demanding bottles..bcs of that my milk is getting low..I used to express breast milk..but may be due to bottle feeding she is having colic pain.( She used to have colic pain while feeding from breast directly)... Now as I have to give formula milk more I am feeding her through    Nipple Shield ...She is accepting NIPPLE shield... My question is how long can I use nipple shield???? ... bcs she is not accepting to feed from breast directly..Is there any side effects of using Nipple Shield???