Lerping blinks

Hi, I have a problem thats been bugging me for a while. Im trying to build some natural facial animation scripts and having trouble with timing. Currently, in this script, I have the character blinking using loops, where I can control the speed, but its very robotic. I would like to be able to lerp the motion to ease in/out the anim but if I try inserting blinkLerp it doesnt finish the motion due to yield not working the way I want or it jumps to open of closed.

As a whole, Id love to find a better way to do this, Lerping at random intervals, but have had little success in achieving it. Any help would be appreciated. Thanks

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class blendCTRL : MonoBehaviour
 {
     int blinkDown = 10;
     int counter = 100;
     bool blinker=false;
     int blendSpeed = 50;
     public int lidHeightMax = 10;
     private SkinnedMeshRenderer skinMeshRenderer;
 
     void Start()
     {
         StartCoroutine(RandomWait());
         skinMeshRenderer = GetComponent<SkinnedMeshRenderer>();
     }
 
     IEnumerator RandomWait()
     {
         while (true)
         {
             yield return new WaitForSeconds(Random.Range(0, 5));
             blinker = true;
         }
     }
 
     void Update()
     {
         skinMeshRenderer.SetBlendShapeWeight(0, blinkDown);
 
         if (blinker == true & blinkDown < counter)
         {
             blinkDown = blinkDown + 10;
         }
         else if (blinkDown == 100)
         {
             while (blinkDown > lidHeightMax)
             {
                 blinkDown--;
             }
             blinker = false;
         }
     }
     void blinkLerp()
     {
         skinMeshRenderer.SetBlendShapeWeight(0, Mathf.Lerp(0, 100, blendSpeed * Time.deltaTime));
     }
 }