Any advice please?

Emma

Hi, from the large dip in temp and the 4 increases after it I thought I ovulated on CD 15 but then got a positive OPK on CD 21. If I ovulated on CD 15 I would be 18 dpo so I am guessing it was CD 21 and temps just don’t reflect it for me? Last cycle was 38 days and I got my positive OPK on digital on CD15 but I now think I must have ovulated later then too. Have had a few BFP and didn’t BD much as hubbie was away. Can any one offer any insight please? Thanks